14.52 Rev 1 - Sonnet Software Exporting Your EM Structure to Sonnet . . . . . . . . . 65 ... Chapter...

14.52 Rev 1.0

At Sonnet, we've been developing 3D planar high frequency EM software since 1983, and our software has earned a solid reputa-tion as the world's most accurate commercial planar EM analysis package for single and multi-layer planar circuits, packages and antennas.

Sonnet Software Inc., founded by Dr. James C. Rautio, is a pri-vate company, entirely dedicated to the development of com-mercial EM software. We take great pride in providing quality technical support for our products with timely response--which we believe to be very important for high-end technical software products.

Sonnet is based in Syracuse, NY, USA with representatives across the globe.

NI AWR MICROWAVE OFFICE INTERFACE - 64-BIT

Published: May 2017

Release 16

Sonnet Software, Inc.

100 Elwood Davis Road

North Syracuse, NY 13212

Phone: (315) 453-3096

Fax: (315) 451-1694

www.sonnetsoftware.com

Copyright 1989,1991,1993, 1995-2017 Sonnet Software, Inc. All Rights Reserved

Registration numbers: TX 2-723-907, TX 2-760-739

Rev 16.54

Copyright Notice

Reproduction of this document in whole or in part, without the prior express written authorization of Sonnet Software, Inc. is prohibited. Documentation and all authorized copies of documentation must remain solely in the possession of the customer at all times, and must remain at the software designated site. The customer shall not, under any circumstances, provide the documentation to any third party without prior written approval from Sonnet Software, Inc. This publication is subject to change at any time and without notice. Any suggestions for improvements in this publication or in the software it describes are welcome.

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The program names, xgeom, emstatus, emvu, patvu, dxfgeo, ebridge, emgraph, gds, cvbridge, emserver, emclient, sonntcds, and sonntawr, sonntawr64, Blink, Co-calibrated, Lite, LitePlus, Level2 Basic, Level2 Silver, and Level3 Gold are trademarks of Sonnet Software, Inc.

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Table of Contents

5

TABLE OF CONTENTS . . . . . . . . . . . . . . . . . . . . . . . . 5

1 THE SONNET BOX . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Coupling to the Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

2 NI AWR MICROWAVE OFFICE INTERFACE 64 BIT . . . . . . . 15

System Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Licensing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

NI AWR Microwave Office Interface Overview . . . . . . . . . . . 19

“Available Simulator is Disabled” Message . . . . . . . 21

Selecting Sonnet as your Simulator . . . . . . . . . . . . . . . . . . 21

Opening a New EM Structure . . . . . . . . . . . . . . . . 21

Selecting Sonnet for an Existing EM Structure . . . . . 24

Editing in Microwave Office. . . . . . . . . . . . . . . . . . . . . . . 26

Microwave Office as EM Structure Editor. . . . . . . . . 27

Globally versus Locally . . . . . . . . . . . . . . . . . . . . 27

Changing the Fill Type. . . . . . . . . . . . . . . . . . . . . 28

Controlling the Subsectioning (Meshing) . . . . . . . . . 30

Simulation Program . . . . . . . . . . . . . . . . . . . . . . 33

Controlling the Analysis Frequencies . . . . . . . . . . . 34

Computing Current Density . . . . . . . . . . . . . . . . . 39

Q-Factor Accuracy . . . . . . . . . . . . . . . . . . . . . . . 41

Advanced Project Options . . . . . . . . . . . . . . . . . . 43

Translation Options (NI AWR to Sonnet) . . . . . . . . . 43

Subsectioning Options . . . . . . . . . . . . . . . . . . . . . 51

Executing the Analysis. . . . . . . . . . . . . . . . . . . . . 56

Solver Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Estimate Memory . . . . . . . . . . . . . . . . . . . . . . . . 58

View Response Data . . . . . . . . . . . . . . . . . . . . . . 60

View Current Density Data . . . . . . . . . . . . . . . . . . 62

Open Sonnet Task Bar . . . . . . . . . . . . . . . . . . . . . 63

View Far Field . . . . . . . . . . . . . . . . . . . . . . . . . . 63

TABLE OF CONTENTS

NI AWR Microwave Office Interface 64 Bit

6

Response Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Working Outside Microwave Office. . . . . . . . . . . . . . . . . . 65

Exporting Your EM Structure to Sonnet . . . . . . . . . 65

Translation Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

Sonnet Features Not Available in NI AWR MWOffice Inter-face . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

Metal Types . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

Port Mapping . . . . . . . . . . . . . . . . . . . . . . . . . . 68

Co-calibrated Port . . . . . . . . . . . . . . . . . . . . . . . 68

Via-Ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

Ports on Ground Plane . . . . . . . . . . . . . . . . . . . . 70

Port Termination and Excitation. . . . . . . . . . . . . . 70

Coordinate System. . . . . . . . . . . . . . . . . . . . . . . 71

3D Viewer Scaling . . . . . . . . . . . . . . . . . . . . . . . 71

Meshing, Current Density Plots and Far Field Plots . . 71

Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

Errors in the Coordinate System . . . . . . . . . . . . . . 72

3 NI AWR MICROWAVE OFFICE INTERFACE TUTORIAL . . . . . 73

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

Tutorial Topics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

Obtaining the Example Project . . . . . . . . . . . . . . . . . . . . 74

Editing in Microwave Office . . . . . . . . . . . . . . . . . . . . . . 80

Selecting Sonnet as your EM Analysis Engine . . . . . . 81

Selecting Analysis Controls . . . . . . . . . . . . . . . . . 82

Running the Simulation. . . . . . . . . . . . . . . . . . . . 85

Native Editor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

Editing your EM Structure in Sonnet . . . . . . . . . . . 91

Adding Dimension Parameters . . . . . . . . . . . . . . . 91

Parameter Sweep . . . . . . . . . . . . . . . . . . . . . . . 96

Viewing the Response Data . . . . . . . . . . . . . . . . 101

Importing the Data File. . . . . . . . . . . . . . . . . . . 107

Running the Simulation. . . . . . . . . . . . . . . . . . . 111

APPENDIX I VIA SIMPLIFICATION . . . . . . . . . . . . . . . . . . . . . . . . 113

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113

Table of Contents

7

Via Array Simplification . . . . . . . . . . . . . . . . . . . . . . . . 113

Via Array Criteria . . . . . . . . . . . . . . . . . . . . . . . 114

Additional Simplify Via Array Options . . . . . . . . . . 114

Simplify Via Array Options . . . . . . . . . . . . . . . . . 114

Number of New Via Metals Created . . . . . . . . . . . 120

Simplified Via Array Loss . . . . . . . . . . . . . . . . . . 120

Bar Via Group Simplification . . . . . . . . . . . . . . . . . . . . . 121

New Via Metals and Bar Via Loss . . . . . . . . . . . . . 122

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122

INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123


8

Chapter 1 The Sonnet Box

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The Sonnet EM analysis is performed inside a six-sided metal box as shown above. This box contains any number of dielectric layers which are parallel to the bottom of the box. Metal polygons may be placed on levels between any or all of the dielectric layers, and vias may be used to connect the metal polygons on one level to another.

The four sidewalls of the box are lossless metal, which provide several benefits for accurate and efficient high frequency EM analysis:

• The box walls provide a perfect ground reference for the ports. Good ground reference is very important when you need S-

The Sonnet six-sided shielding box. The metal walls of the box are transparent to allow you to see the interior of the circuit.

Metal Side Walls

Metal Box Top


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parameter data with dynamic ranges that might exceed 50 or 60 dB, and Sonnet’s sidewall ground references make it possible for us to provide S-parameter dynamic range that routinely exceeds 100 dB.

• Because of the underlying EM analysis technique, the box walls and the uniform grid allow us to use fast-Fourier transforms (FFTs) to compute all circuit cross-coupling. FFTs are fast, numerically robust, and map very efficiently to computer processing.

• There are many circuits that are placed inside of housings, and the box walls give us a natural way to consider enclosure effects on circuit behavior.

As an example, a microstrip circuit can be modeled in Sonnet by creating two di-electric layers: one which represents your substrate, and one for the air above the substrate. The metal polygons for the microstrip would be placed on the metal lev-el between these two dielectric layers. The bottom of the box is used as the ground plane for the microstrip circuit. The top and bottom of the box may have any loss, allowing you to model ground plane loss.

Coupling to the Box

Since the four sidewalls of the box are lossless metal, any circuit metal which is close to these walls can couple to the walls - just like what would happen if you fabricated and measured a real circuit with the same box. If you do not want to model this coupling (for example, your real circuit does not have sidewalls), then you must keep the circuit metal far away from the box sidewalls. A good rule to use is at least three to five substrate thicknesses as shown below.

This circuit has a substrate of 25 mils. The spiral should be kept at least 75-125 mils from the box walls.


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All Sonnet geometry projects are composed of two or more dielectric layers. There is no limit to the number of dielectric layers in a Sonnet geometry project, but each layer must be composed of a single dielectric material. Metal polygons are placed at the interface between any two dielectric layers and are usually mod-eled as zero-thickness, but can also be modeled using Sonnet’s thick metal model. Vias may also be used to connect metal polygons on one level to metal on another level.

You will use the Dielectrics dialog box (Circuit Dielectric Layers), as shown below, to add dielectrics to your circuit. Each time a new dielectric layer is added, a corresponding metal level is also added to the bottom of the new dielectric layer. You may also add dielectric layers in the Stackup Manager.

This example shows a 3-D drawing of a circuit (with the z-axis exaggerated). Please note that the pictured circuit is not realistic and is used only for purposes of illustrating the box setup.

Below is a glossary of some commonly used terms in Sonnet which relate to the box model.

Metal Bottom (Ground Plane). This is not shown in the Dielectric Layer dialog box

Dielectric Layer

Metal Level

0

1

2

Note that the number of the metal level appears in between the dielectric layers.


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Dielectric Layer: This refers only to dielectrics, NOT metals. In the example above, there are four dielectric layers. There is an entry for each dielectric layer in the Dielectric Layers dialog box (Circuit Dielectric Layers).

Metal Level: Metal levels are modeled as zero thickness and are attached to the dielectric layer ABOVE them. In the example above, there are three metal levels in addition to the box top and bottom. Since no metal may be placed on the top of the box, it may not be accessed by the user or viewed in the project editor. The bottom of the box is referred to as the GND level and may be accessed in the proj-ect editor. It is not labeled in the dielectric window. The top and bottom of the box are lossless metal by default, but can be changed in the Box Settings dialog box (Circuit Box Settings). You can use as many different metal types as you wish on a single metal level; for instance, you may use a silver polygon and copper polygon on the same metal level.

NOTE: A “layer” refers to a dielectric layer while “level” refers to the metal level which is sandwiched between the two dielectric layers. So, technically, there is no such thing as a “metal layer” in Sonnet.

GND Level: You can place polygons on the GND level, but they have no effect because this level is already completely metalized. However, cases do exist in which you may want to place a polygon on the GND level in order to place a via or a dielectric brick there.

Viewing Levels: When you view your circuit in the normal 2D view in the proj-ect editor, you are always “on” a particular level, as shown by the level drop list in the Project Editor tool bar as shown below. The top level is always “0” and in-creases as you move downward through the box. You can switch levels by using


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your arrow keys, or using the level drop list. By default, all polygons on your pres-ent level are shown in Fill, and all polygons on all other levels are shown as dashed outlines.

As mentioned above, the metal level is associated with the dielectric layer above, such that when you delete a dielectric layer, the metal level directly below the lay-er is deleted.

The total height of the box is determined by the sum of the thicknesses of the di-electric layers since metal is either modeled as zero-thickness or protrudes into the dielectric layer above. If you wish to model microstrip circuits, you will need to place a thick layer of air above your circuit; i.e., the topmost dielectric layer should be at least three to five times the substrate thickness.

Level 0 is displayed in the level drop list in the project editor.

You may also change the view to other metal levels by using the Up One Level and Down One Level button on the project editor tool bar.

Level 0

Level 1

The dotted outline indicates metal on the level below this one.

The dotted polygon seen above is shown on Level 1 which is below Level 0.


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Chapter 2 NI AWR Microwave Office Interface 64 Bit

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Sonnet’s Microwave Office Interface (MOI) provides a completely integrated “solver on request” interface between NI AWR’s Microwave Office (Version 13 and above) and Sonnet software. The interface allows you to stay completely in the Microwave Office environment using Sonnet as your EM analysis engine, or you may choose to edit your circuits in the Sonnet environment before running the EM analysis. Either way your results are easily integrated back into the Micro-wave Office environment.

NOTE: The NI AWR Microwave Office Interface only supports geometry projects. It is not possible to translate a netlist project from Sonnet.

This manual assumes that you are familiar with the basics of using both Sonnet and Microwave Office. If this is not true, we recommend referring to the appro-priate documentation for whichever program you need to learn. If you are new to Sonnet, we suggest performing the tutorials in the Sonnet Getting Started man-ual, available in PDF format through the Sonnet task bar.


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System Requirements

This manual is for Sonnet’s NI AWR Microwave Office Interface for 64 bit ver-sions. The 32-bit interface supports NI AWR Microwave Office Version 11 - 32 bit and below. If you are interested in the interface for the 32- bit version, please see the Sonnet NI AWR Interface 32 Bit manual.

For up to date requirements and testing status, please refer to:

http://www.sonnetsoftware.com/requirements

Installation

The NI AWR MWOffice Interface is NOT automatically installed when you per-form your Sonnet installation. Once the Sonnet installation is complete, you should do the following to install the NI AWR MWOffice Interface:

1 Open NI AWR Microwave Office.

If you do not know how to open the NI AWR Microwave Office, please refer to the NI AWR Microwave Office documentation. The Microwave Office window is opened on your display.

Tools Menu

http://www.sonnetsoftware.com/requirements


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2 Select Tools Configure 3rd Party EM Solvers from the main menu of the Microwave Office window.

The Configure 3rd Party EM Solvers dialog box appears on your display. The available EM simulators are listed in the window.

! WARNINGIf the “Configure 3rd Party EM Solvers” command does not appear in the Tools menu, then NI AWR Microwave Office is not correctly configured to use Sonnet as the EM Solver. Please ensure that you have an EM Socket license for Microwave Office and that the program is correctly configured to use a 3rd party solver (File License Feature Setup). Please refer to your system administrator and NI AWR Microwave Office documentation for more information.


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3 Click on the Sonnet Simulator in the list to select it.

The Sonnet Simulator entry is highlighted in blue.

4 Click on the Install button in the Configure 3rd Party EM Solvers dialog box.

A browse window is opened that allows you to choose an EM Solver Configuration File (.xsd). Select the following file:

<Sonnet Directory>\resource\awr64\SONNET_solver_schema.xsd

where <Sonnet Directory> is the directory in which Sonnet is installed.

5 Once you have selected the file, click on the Open button in the Browse window.

The Configure 3rd Party EM Solvers dialog box is updated and only the Sonnet Simulator solver is selected.

6 Click on the OK button to close the dialog box and apply the changes.

A message box appears with the message “You must restart the application for the changes to take effect.” You should close NI AWR Microwave Office and restart the program. This completes the installation of Sonnet Software.

! WARNINGThe name of the Sonnet simulator is different in the 32-bit and 64-bit interfaces. When you open a project in Microwave Office, if a query box appears with the message “Available Simulator is Disabled,” it is imperative that you answer “No” in the query box. The correct simulator is chosen later.

Install button


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Licensing

The NI AWR Microwave Office Interface 64 bit may be purchased as an option for Sonnet Level2 Basic or above. Please see your system administrator if you are unsure of the availability of this feature.

NI AWR Microwave Office Interface Overview

The NI AWR Microwave Office Interface uses the EM Socket in NI AWR’s Mi-crowave Office to provide Sonnet’s analysis engine, em, as the “solver on re-quest”. You may choose to edit your EM Structure in Microwave Office or in Sonnet’s project editor. However, if you choose to edit your EM structure in Son-net’s project editor, you must analyze in the Sonnet environment and manually import the resulting data into NI AWR Microwave Office.

For users who have previously used the NI AWR Microwave Office 32 bit ver-sion, there have been some major changes made by NI AWR in their EM Socket which have affected how the Sonnet interface operates and what features are avail-able.

• If you wish to remain in the NI AWR Microwave Office environment and launch your Sonnet analysis from there, you must edit your EM structure in NI AWR Microwave Office. NI AWR Microwave Office no longer allows you to choose a native editor to use in their environment.

• You may still open your EM Structure in Sonnet’s project editor and make changes, but you may no longer import your Sonnet project back into NI AWR Microwave Office after editing in the Sonnet’s project editor. As mentioned above, if you edit in Sonnet, you must remain in the Sonnet environment until you produce your analysis results, which can then be imported back into NI AWR Microwave Office (for details, please see Chapter 3 "NI AWR Microwave Office Interface Tutorial" on page 73).


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When you edit your EM Structure in Microwave Office, the geometry is sent to Sonnet for analysis and only the analysis results are sent back to Microwave Of-fice, as shown below.

If you choose the Native Editor, Sonnet’s project editor, to edit your geometry, the EM Structure is sent to Sonnet, changes are made in Sonnet, you run the EM anal-ysis and then must manually import the analysis results back into Microwave Of-fice. Any changes made in the native editor do not affect the EM structure in Microwave Office. (The Sonnet project is not imported back into Microwave Of-fice as it could be in the 32 bit version of the interface.) This mode is pictured be-low.

NI AWR Microwave

Office

em

Sonnet’s analysis engine

Geometry

MWOffice Editor

Response Data (Automatic)

NI AWR Microwave

Office

em

Sonnet’s analysis engineSonnet’s project editor

Geometry

Geometry

ResponseData(Manual)


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“Available Simulator is Disabled” Message

If you open an older project created in the 32-bit interface in the newer 64-bit in-terface, or have installed both the 32-bit and 64-bit versions of NI AWR Micro-wave Office and the Sonnet interface, when you attempt to open a project in Microwave Office a query box appears:

Click “No” in response to the query.

! WARNINGThe name of the Sonnet simulator is different in the 32-bit and 64-bit interfaces. This message indicates that the software is attempting to access the 32-bit simulator. It is imperative that you answer “No” in the query box. You will select the correct, 64-bit, analysis engine later.

Selecting Sonnet as your Simulator

You may select Sonnet as your EM Simulator using one of two methods:

Opening a New EM Structure

When you open a New EM Structure in Microwave Office, you are prompted to choose which analysis engine you wish to use. In order to select Sonnet do the fol-lowing:


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1 Open your Microwave Office Project in Microwave Office.

The Microwave Office window with the project browser window on the left hand side, appears on your display.

Project Browser Window


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2 Right-click on EM Structures in the project browser and select “New EM Structure” from the pop-up window which appears.

The New EM Structure dialog box appears on your display.

3 Click on the “Sonnet Simulator 3D Planar -Async” radio button.

This selects Sonnet’s em as your analysis engine for electromagnetic simulations within Microwave Office.

4 Enter the desired name for the new EM Structure in the Name text entry box at the top of the dialog box.

This will identify the EM Structure in the Microwave Office project.

Sonnet radio button


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5 Click on the Create button to create the new EM Structure and close the dialog box.

The new structure will appear in the project browser and a blank layout appears in the Microwave office window as shown below. The new structure in this example is “Demo Filter.”

Selecting Sonnet for an Existing EM Structure

To select Sonnet as the EM Simulator for an existing EM Structure in your Micro-wave Office project, do the following:

1 Open your Microwave Office Project in Microwave Office.

The Microwave Office window with the project browser window on the left hand side, appears on your display.

The new EM Structure


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2 Right-click on the desired EM Structure in the project browser and select “Set Simulator” from the pop-up menu which appears.

The Select a Simulator dialog box appears on your display.


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3 Select the “Sonnet Simulator 3D Planar - Async” radio button,

4 Click on the OK button to apply the changes and close the dialog box.

This completes selecting Sonnet as the EM Simulator.

Editing in Microwave Office

When you select Sonnet as your analysis engine, you have a choice as to where you will edit the EM Structure: in Microwave Office or in Sonnet’s project editor, known as the Native Editor. This next section discusses editing your structure in the Microwave Office environment.

You edit your EM Structure in Microwave Office when your structure does not use any advanced features unique to Sonnet such as parameters, or dielectric bricks. (For a complete list of features available only in Sonnet, see "Translation Issues" on page 66).

When you use Microwave Office as your editor, you may use the analysis controls provided by the NI AWR Microwave Office Interface in the Microwave Office menus and dialog boxes to control the analysis frequencies and run options. When you request an analysis, the geometry specification for the EM Structure entered in Microwave Office is passed to Sonnet and only the resulting analysis data is re-turned to Microwave Office.


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Microwave Office as EM Structure Editor

Microwave Office is the default editor for all EM Structures. All editing and changes to your EM Structure will be made in the Microwave Office editor. When you double-click on the EM Structure, the circuit is opened in the right hand pane of the Microwave Office window where you may edit it. This limits you to using features that are available in both Microwave Office and Sonnet. Please see "Translation Issues" on page 66 for a list of features which do not translate be-tween Microwave Office and Sonnet.

Globally versus Locally

You may define options globally so that the settings are used for all EM structures in your NI AWR Microwave office project or you may define local options which apply only to a particular EM structure.

To apply settings globally, you will right-click on EM Structures in the directory tree and select Options from the pop-up menu which appears. The Options dialog box is opened,

To apply settings locally, you will right-click on the desired EM structure in the directory tree and select Options from the pop-up menu which appears. The EM Options dialog box is opened.

The Options dialog box and EM Options dialog boxes contain the same settings but these settings are applied to either all structures (Global) or just the selected structure (Local). So the instructions below may be used for both Global and Local settings. All of the settings and options affecting Sonnet may be found in the Op-tions and EM Options dialog boxes on the Sonnet tab.


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Changing the Fill Type

You may control the fill type used in Sonnet for metal polygons. The default fill type for Sonnet is staircase fill. In this case, small cells are used to approximate curved or diagonal edges as shown below.

The conformal mesh fill type and the diagonal fill type are used to more accurately model curved and diagonal edges respectively. In Sonnet’s editor, you may apply these fill types on a per polygon basis; however, when editing in Microwave Of-fice, you may apply these fill types on a global, or local basis, but you may not change the fill type of an individual polygon. For a detailed discussion on fill types and how they affect subsectioning in Sonnet, please refer to Chapter 3, “Subsec-tioning” in the Sonnet User’s Guide.

Setting Sonnet Fill Type Globally

To apply the Conformal or Diagonal Fill option to all existing and new EM Struc-tures in your Microwave Office project, do the following:

1 Right-click on the “EM Structures” entry in the project browser and select “Options” from the pop-up menu which appears.

The Options dialog box appears on your display.

The two polygons are identical. Notice that the dark outline on the bottom polygon indicates the polygon input by the user in Sonnet. The upper polygon shows the actual metalization analyzed by em. As you can see, a “staircase” is used to approximate a curved edge.


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2 Click on the Sonnet tab in the Options dialog box.

The dialog box should appear similar to the graphic below.

3 Click on the Default Metal Fill Type entry under Subsectioning Options.

The Default Metal Fill Type entry is highlighted in blue and a droplist arrow appears at the end of the entry row.

4 Select the desired fill type, Staircase, Conformal Mesh or Diagonal Fill, from the droplist.

This will become the default for all metalization in all EM Structures in your Microwave Office project. This setting may also be changed locally for a particular EM Structure (see “Setting Sonnet Fill Type Locally,” page 30).

DefaultMetalFill Type

Droplist


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5 Click on the OK button to apply the changes and close the dialog box.

The fill type will default to your selection whenever a new EM Structure is created in this Microwave Office project.

Setting Sonnet Fill Type Locally

To set the fill type locally, follow the instructions for the Global setting in the sec-tion above, but start by right-clicking on the desired EM Structure name in the project browser.

Controlling the Subsectioning (Meshing)

Sonnet allows you to control how cells are combined into subsections for each polygon. This is done using the parameters “X min”, “Y min”, “X max” and “Y max.” These parameters may be changed for each, allowing you to have coarser resolution for some polygons and finer resolution for others. These parameters may be accessed in Microwave office as follows:

1 Right-click on EM Structures in the project tree if you wish to apply the set-tings globally. Right-click on the desired EM structure if wish to apply the settings locally.

A pop-up menu appears.

2 Select “Options” from the pop-up menu.

The Options dialog box is opened (Global) or the EM Options dialog box (Local) is opened.


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3 If it is not already selected, click on the Sonnet tab in the Options dialog box.

4 Click on the Show Secondary button in the Options dialog box.

This expands all of the options in the dialog box so that all possible options are displayed.

5 Scroll down to “All Polygon Meshing (MWO to Sonnet)” under “Advanced Subsectioning on the Sonnet tab.

The Options dialog box should appear similar to the illustration below.

ShowSecondarybutton

Subsectioning Controls


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6 To change a value, click on the checkbox for the desired entry.

When you enable a setting, a line appears below which allows you to input the de-sired value. The example below shows a value of 25 entered for the XMin setting.

For a detailed discussion of these parameters and how they affect subsectioning in Sonnet, please refer to "Changing the Subsectioning of a Polygon" on page 35 of the Sonnet User’s Guide.

XMin

XMinvalue


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Simulation Program

Sonnet allows a user to run simulations on their own computer using a local copy of the analysis engine, em, or to submit the job to an analysis engine running on another computer (Remote em) or even on a processing cluster (emCluster). You can use settings in the Sonnet window to determine which processor runs the anal-ysis. The Simulation Options entry in the Sonnet tab of the Options dialog box al-lows you to control this.

Enable Remote/Cluster Simulation: This option allows the software to de-termine the processor settings for Sonnet on your computer and submit the job to your default processing choice. Select Local or Remote from the droplist which appears when you select the option.

Selecting the Local option runs your simulation on a locally installed copy of the analysis engine.

NOTE: If you do not have a local copy of the analysis engine, you must set up Remote em and select Remote for this field. If Local is selected and a local copy is not available, then the simulation fails.

Selecting the Remote option runs your simulation on a remotely installed copy of the analysis engine. For more information on configuring and using Remote em, please refer to the Remote em Computing manual. For more information on con-figuring and using emCluster, please refer to the emCluster Computing manual.

SimulationProgram

Droplist


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Controlling the Analysis Frequencies

You may control the range of analysis frequencies as well as the type of frequency sweep used for your Sonnet analysis from the Options dialog box in Microwave Office. You are limited to either analyzing at the points requested by Microwave Office or performing an Adaptive Band Sweep on a full or partial band.

Sonnet's Adaptive Band Synthesis (ABS) performs a fine resolution analysis of a specified frequency band. Em analyzes the circuit at the beginning and end fre-quencies. Using an iterative process, em then analyzes at other discrete frequen-cies and determines a rational polynomial fit to the S-parameter data within the frequency band. Once a rational polynomial fit is achieved with an acceptable er-ror, the frequency response across the specified bandwidth is calculated. If your Microwave Office simulation requires more than 4 or 5 frequency points, an Adaptive Sweep using ABS is the most efficient way to obtain the desired results.

TIP

When using an ABS sweep, em produces the simulation data for 300 points in ap-proximately the same amount of time as 10 data points.

You will usually want to avoid using the Local frequency controls in Microwave Office, especially when the local controls request fewer data points than the Glob-al Frequencies. Microwave Office uses the data obtained in the Local Frequencies to interpolate or extrapolate the Global frequency data. Since an ABS sweep in Sonnet can produce approximately 300 data points from just a few discrete data points, it is more efficient and accurate to only specify frequencies in the Global controls and use the data from Sonnet’s analysis.

For example, assume the Global frequency control in Microwave Office is set to do an analysis from 1 to 10 GHz in steps of 0.1 GHz. This would require the anal-ysis of the EM Structure at 91 frequency points. Also assume that the Local con-trols specify only 11 frequencies from 1 to 10 GHz and you specify an ABS sweep on the Full Band which in this case is 1 GHz to 10 GHz. When the Simulate Analyze command is selected in Microwave Office, the Sonnet analysis engine, em, performs an ABS sweep from 1 GHz to 10 GHz producing approximately 300 data points across this band. The only data which is returned, however, are the 11 frequency points from 1 to 10 GHz in steps of 1 GHz as shown in the illustration below. Microwave Office would interpolate between these points to produce the


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Global Frequency points. Therefore, the most efficient way to analyze your EM Structure is to specify all the desired frequencies in your Global controls in Mi-crowave Office and specify an ABS sweep in Sonnet’s em.

You use the Adaptive Sweep Settings on the Sonnet tab of the Options dialog box to specify the frequency controls for your Sonnet analysis. To open this page, right-click on the EM Structure and select “Options” from the pop-up menu, then click on the Sonnet tab in the dialog box which appear. Scroll down to the Adap-tive Sweep Settings option. Note that if you wish to use the Advanced ABS set-ting, you should click on the Show Secondary button in the Options dialog box. The settings and their use are described below:

Use Adaptive Band Synthesis (ABS): Select this checkbox to run an ABS sweep in Sonnet when the EM Structure is analyzed. Note that although an ABS sweep produces approximately 300 data points, only those data points requested by Microwave Office are returned from Sonnet. This checkbox is selected by de-fault. If you do not want to run an ABS sweep, but want only to analyze at the re-quired points set in Microwave Office, clear this checkbox.

NI AWR’s Micro-wave Office - 91 Global data points and 11 Local data points

GeometrySonnet’s em ABS sweep produces 300 data points11 Points

(289 data points discarded)

Adaptive SweepSettings


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ABS Band Selection: Select Full-Band from this droplist when you wish to per-form the ABS sweep on the Full Band required by Microwave Office. This band is defined by the lowest and highest frequencies requested by Microwave Office. This droplist only appears when the Use Adaptive Band Synthesis (ABS) check-box is selected. This is the default setting for an ABS sweep. When this checkbox is selected, then the Analysis Control in the Analysis Setup dialog box (Analysis Setup) in Sonnet’s project editor is Adaptive Band Synthesis.

Select “Select-Band” from the ABS Band Selection droplist when you wish to per-form an ABS sweep over a different frequency band than the one required by Mi-crowave Office. This may be part of the full band, overlap the full band or be an entirely different band. When Select-Band is selected, then the Analysis Control in the Analysis Setup dialog box (Analysis Setup) in Sonnet’s project editor is Adaptive Sweep (ABS) and the frequency band is the one entered in this dialog box.

Note that if Microwave Office has requested frequencies out of this select band for which data does not already exist, em will have to run a full analysis at each requested data point which lies outside the select band. This may significantly in-crease processing time in the EM simulation.

Select-Band Start Frequency: Enter the lowest frequency of the desired fre-quency band here. These entries are only used when a Select-Band Adaptive Band Synthesis is selected.

Select-Band Stop Frequency: Enter the highest frequency of the desired fre-quency band here. These entries are only used when a Select-Band Adaptive Band Synthesis is selected.


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Advanced ABS Settings

The Advanced ABS Options are visible in the Sonnet tab of the Options dialog box when the Show Secondary button has been selected. These options allow you to control the ABS Caching Level and the ABS Frequency Resolution. The con-trols are explained below.

Sonnet ABS Caching Level: The ABS caching level determines if and how much of the ABS caching data is stored in your project. You select the desired lev-el from the droplist that appears when you select Sonnet ABS Caching Level in the Options dialog box. The levels are detailed below.

NOTE: These settings are only pertinent if you plan on simulating in the Sonnet environment and importing the response data into Microwave Office.

• None: Select this option if you do not wish to store any ABS cache data in your project. If this option is selected and you stop an ABS analysis before completion, the only data available is the data calculated for the discrete data points. When you resubmit the ABS job, the cache data will need to be recal-culated. Thus, the analysis must start all over again.

• Stop/Restart: Select this option to store the ABS cache data while an ABS analysis is running. This allows you to stop an ABS analysis and restart it at a later time without losing the data from the processing done before the stop. This option deletes the cache data when convergence is reached and the ABS analysis is completed. This is the default setting.


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• Multi-Sweep plus Stop/Restart: Selecting this cache level saves the ABS cache data for every analysis performed on the project. This saves you processing time on any subsequent ABS analyses but be aware that the cache data will be calculated for any analysis of the project including non-ABS types of analysis, increasing the project size. This option should be used when you think you might want to re-analyze the project, using different ABS rang-es or settings.

It is important when using this option that all your analyses use the same subsec-tioning frequency. This ensures that any pre-existing ABS cache data can be used in the present analysis. The default setting used to determine the subsectioning fre-quency is to use the highest frequency from the present analysis job. If you per-form multiple sweeps over different frequency bands then the cache data from one run will be invalid for the next, since the subsectioning frequency would be dif-ferent. In order to avoid this you should use the controls for the subsectioning fre-quency found in Sonnet’s Advanced Subsectioning dialog box to ensure that the same frequency is used for all analyses. For more details about setting the subsec-tioning frequency, please see "Advanced Subsectioning Options" on page 51.

ABS Frequency Resolution per Sweep: The resolution provides the mini-mum value of the gap between data points in an ABS sweep. This can be calculat-ed automatically by em or input by the user.

• Automatic: The resolution of the frequency band used in an ABS analysis is determined by the analysis engine, em. This is the default setting. The au-tomatic setting provides approximately 300 frequency points in the band.

• Manual: If you wish to set the resolution for an ABS analysis, select this ra-dio button and enter the desired resolution in the adjacent text entry box. The units for this value are the presently selected frequency units for the project.

There are several things to be aware of when using the manual setting for the ABS resolution. Coarse resolution does not speed things up. Once a rational polynomial is found to ''fit'' the solution, calculating the adaptive data uses very little processing time. A really coarse resolution could produce bad re-sults by not allowing the ABS algorithm to analyze at the needed discrete fre-quencies. Fine resolution does not slow down the analysis unless the number of frequency points in the band is above approximately 1000 - 3000 points. A step size resulting in at least 50 points and less than 2000 points is recom-mended.


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Computing Current Density

There is a run option available in a Sonnet analysis which allows you to compute current density data as part of the simulation. Selecting the Compute Currents checkbox in the Sonnet tab of the Options dialog box turns on this run option. Note that if you are running an Adaptive Band Sweep, current density data is only cal-culated for the discrete data points, not for all of the adaptive data.

NOTE: The current density data produced by Sonnet must be viewed using Sonnet's current density viewer. The current density data generated by the analysis engine, em, is not compatible with the Microwave Office framework. All selections in the Animate menu in Microwave Office are disabled when Sonnet is selected as the simulator.

Selecting the Run Option

To calculate current density data as part of your Sonnet analysis, do the following:

1 Right-click on the desired EM Structure (for which Sonnet has been selected as the simulator) and select Options from the pop-up menu which appears.

The EM Options dialog box appear on your display.

2 Click on the Sonnet tab in the dialog box.

This displays the Sonnet options.


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3 Scroll down until the Project Options are visible in the display window.

4 Click on the Compute Currents checkbox.

When the Sonnet analysis is executed, current density data will be calculated for all discrete data points.

5 Click on OK to close the dialog box and apply the changes.

Viewing the Current Density Data

Once the analysis is complete and current density data is available, you may view the current density data in Sonnet by doing the following:

1 Right-click on the name of the EM Structure and select “Open in Native Edi-tor” from the pop-up menu which appears.

Sonnet’s project editor is opened displaying the translated Sonnet project.

2 Select Project View Currents from the main menu of Sonnet’s project editor.

Sonnet's current density viewer allows you to view the current density data and animate the view as a function of time or frequency. For more information, see "View Current Density Data" on page 62.

ComputeCurrentscheckbox


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Q-Factor Accuracy

When performing an ABS sweep, there is an option to increase the Accuracy of the Q-Factor. The Q-Factor is the quality factor of the project and is calculated us-ing this formula:

Selecting this option increases the accuracy of the Q-factor when ABS is used. Normally ABS uses S-parameters to determine convergence. When this option is used, ABS uses both the S-parameters and Q-factor for convergence criteria. This option should be used whenever you plan on viewing/calculating Q-factor, but could require more discrete frequencies.

Selecting the Run Option

To select Q-factor Accuracy as part of your Sonnet analysis, do the following:


The EM Options dialog box appear on your display.



Q Factor– Yimag nn Ynnreal( )⁄=


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3 Scroll down until the Project Options are visible in the display window.

4 Click on the Q-Factor Accuracy checkbox.

When the Sonnet analysis is executed, the convergence calculations for ABS will use the Q-factor accuracy as well as S-parameter data.

Q-FactorAccuracy


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5 Click on OK to close the dialog box and apply the changes.

Advanced Project Options

There are a number of advanced project options available in the Sonnet tab of the Options dialog box. The Show Secondary button must be selected in order to dis-play the Advanced Project Options. The Advanced Project Options appear under the Project Options in the Options dialog box in Microwave Office.

By default, the De-Embed option is on, and all other options are off. To turn on an option, click on the appropriate checkbox. For information on any of the available options, please refer to Sonnet’s help which may be accessed by selecting Help

Sonnet Help from any Sonnet application menu. You may locate the desired infor-mation by searching in the index under the run option name.

Translation Options (NI AWR to Sonnet)

You are able to control how many of the circuit elements are translated when mov-ing from the NI AWR environment to the Sonnet Project environment.

There are a number of options available in on the Sonnet tab of the Options dialog box in Microwave Office under Translation Options. The Show Secondary button needs to be selected to display the Advanced Translation options.

AdvancedOptions


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To access these options, do the following:


The Options dialog box appear on your display.



3 Scroll down to “Translation Options” in the Options dialog box.

4 If it is not already selected, click on the Show Secondary button in the Options dialog box.

This displays all of the translation options including the advanced translation options. All of the options are detailed below.

Convert Single Vias: This option places a bounding box on vias being imported and creates a rectangular via the size of the bounding box in place of the imported via.

Simplify Via Arrays: This option locates via arrays and performs simplification to create one equivalent via in Sonnet to represent the via array in order to increase analysis efficiency by reducing the memory and processing requirements for the circuit. This feature automatically performs this simplification during the transla-tion process using controls set by the user. For a detailed discussion of Via Array Simplification, please see Appendix I "Via Simplification" on page 113. The op-tions which control simplification are available in the advanced translation op-tions under Simplify Via Array Options.

TranslationOptions


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The advanced translation options are divided into three sections: Process Stackup and Geometry Options, Simplify Via Array Options, and Port Conversion Op-tions. Each option is followed by a checkbox; select the checkbox if you wish to use the option. Each section is discussed below.

The various options are detailed below:

Process Stackup and Geometry Options

All Thick Metal: Converts all metals which use a conductivity and thickness set-ting in your EM structure to the Thick Metal metal type in the destination Sonnet project. Thin film resistors are not converted. For more information about Son-net’s metal types, please refer to "Creating Planar Metal Types" on page 50 of the Sonnet User’s Guide.

All Lossless Metal: Converts all metal in your EM structure to the Lossless met-al type in the destination Sonnet project. For more information about Sonnet’s metal types, please refer to "Creating Planar Metal Types" on page 50 of the Son-net User’s Guide.

All Lossless Dielectrics: Converts all dielectrics in your EM structure into lossless dielectrics in the destination Sonnet project. For more information on Sonnet’s modeling of dielectric loss, please refer to "Dielectric Layer Loss" on page 66 of the Sonnet User’s Guide.

ProcessStackupandGeometryOptions


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Remove Unused Materials: Removes any defined materials such as planar metal types, via metal types or dielectrics that are not used in the translated Sonnet project. The only materials defined in the resulting Sonnet project are materials used in the Sonnet project. Selected by default. If this option is turned off, all ma-terials defined in the Microwave Office project are translated.

Union Geometry: Merges any adjacent metal polygons with the same metal properties. If a polygon has another geometry element attached, such as a port, it will not be merged. This option is probably best used for the flow of a layout that has been generated from a schematic with MLIN, MCURVE, etc. using NI AWR's EM extraction.

Add Via Pads: Adds a Fill metal pad to the top and bottom of any via which does not already have a pad at the bottom or top in the geometry being input. The pad is created using the same metal type as the via. Note that the via pad is added by the Sonnet analysis engine prior to analyzing and is not shown in the Sonnet’s project editor 2D view. It is, however, visible in the 3D view in the project editor.

Thick Metal Naming: There is a naming convention for a metal type in NI AWR which will be converted to the Thick Metal metal type in Sonnet. Please see “Modeling Thick Metal,” page 68 for details about the naming convention. This option is on by default. If you do not wish to use the naming convention, clear this checkbox.

Model Vias as Solid: Via metal types are created in the Sonnet project to model via polygons. The loss model used for these via metal types is the Volume loss model for which you can choose to model your vias as hollow or solid. Selecting this check box will model all of your vias as solid. For more information on the Volume Loss model and the “solid” setting, please refer to "Volume Loss Model" on page 59 of the Sonnet User’s Guide.


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Edge Ports (non-open-ended): This is a global setting and controls how open-ended edge ports in Microwave Office are modeled in Sonnet. An edge port in Sonnet may only occur on the box wall. If a port is on a polygon edge and is not on the box wall, this creates an error condition. How this error condition is handled is controlled by this setting.

There are two choices.

• Convert to Auto-Gnd: The port can be converted to an auto-grounded port. For more information about auto-grounded ports, see “Automatic-Grounded Ports,” page 99 in the Sonnet User’s Guide.

• Convert to Co-cal: The port can be converted to a co-calibrated port in Sonnet. Note that the co-calibrated ports are automatically grouped after translation by the analysis engine. For more information on co-calibrated ports, please see “Co-calibrated Internal Ports,” page 89 of the Sonnet User’s Guide. This is the default setting.

Internal Ports (non-opened ended): This is a global setting and controls how via ports in between two metal polygons in Microwave Office are modeled in Sonnet. There are two choices.

• No conversion: The via port is modeled as a via port in the Sonnet project.

• Convert to Auto-Gnd: The port can be converted to an auto-grounded port. For more information about auto-grounded ports, see “Automatic-Grounded Ports,” page 99 in the Sonnet User’s Guide. This is the default setting.

Correct

Error Condition

Edge port in NI AWR’s Microwave Office


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Via Ports: Via ports in Microwave Office are often created as part of an EM extraction from a schematic representation to an EM structure. The via ports are created as placeholder ports to connect a component schematic.

The translation process for via ports may revert to using the edge port or internal port setting depending upon the placement of the via port. For example, if a via port is in between two pieces of metal, the translation will use the internal port setting. A via port internal to a metal polygon cannot translate to a co-calibrated or Auto-ground port without generating an error in Sonnet and will therefore be translated as a via port. Sonnet's port translation will always attempt to find the closest polygon edge to place a Sonnet port.These via ports may be converted as follows:

• No conversion: You can choose not to convert the port at all; the port appears as a via port in the destination Sonnet project.

• Convert to Auto-Gnd: The port can be converted to an auto-grounded port. For more information about auto-grounded ports, see “Automatic-Grounded Ports,” page 99 in the Sonnet User’s Guide.

• Convert to Co-cal: The port can be converted to a co-calibrated port in Sonnet. Note that the co-calibrated ports are automatically grouped by the analysis engine after translation. For more information on co-calibrated ports, please see “Co-calibrated Internal Ports,” page 89 of the Sonnet User’s Guide. This is the default setting.

These nodes are modeled as via ports in the extraction.


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Via Array Translation Options

This section of the dialog box contains the options which control how the via array simplification is performed when a circuit is translated into Sonnet. For a detailed discussion of these controls, please refer to “Simplify Via Array Options,” page 114.

Additional Simplify Via Array Options: This field may be used to enter addi-tional command line options and should only be used at the direction of Sonnet support personnel.

Simplify ViaArray Options


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Port Conversion Options

Open Ended Ports: This is a global setting and controls how open-ended edge ports in Microwave Office are modeled in Sonnet. An edge port in Sonnet may only occur on the box wall. If a port is on a polygon edge and is not on the box wall, this creates an error condition. How this error condition is handled is con-trolled by this setting.

There are three choices.

• No conversion: You can choose not to convert the port at all; the port does appear in the destination Sonnet project and an error occurs when you attempt to run a simulation.

• Convert to Auto-Gnd: : The port can be converted to an auto-grounded port. For more information about auto-grounded ports, see “Automatic-Grounded Ports,” page 99 in the Sonnet User’s Guide.

• Convert to Co-cal: The port can be converted to a co-calibrated port in Sonnet. Note that the co-calibrated ports are automatically grouped after translation by the analysis engine. For more information on co-calibrated ports, please see “Co-calibrated Internal Ports,” page 89 of the Sonnet User’s Guide. This is the default setting.

Correct

Error Condition

Open Ended Edge port in NI AWR’s Microwave Office


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Subsectioning Options

This section of the Sonnet options allows you to control your subsectioning. You can control a majority of your projects subsectioning through use of the Analysis Speed/Memory Control. The three options are detailed below:

Fine/Edge Meshing: Em uses the XMIN and YMIN settings of each individual polygon, and the edge meshing settings of each individual polygon. This is the de-fault setting. It uses the most memory and returns the most accurate answer.

Coarse/Edge Meshing: Em checks the Xmin value of each individual polygon. If the value is less than 50, em uses 50. Otherwise, em uses the Xmin value of that polygon. Same for Ymin. Em uses the edge meshing settings of each individual polygon.

Coarse/No Edge Meshing: Xmin and Ymin are treated the same as cited for the option above, but em disables edge meshing for all polygons. This setting uses the least amount of memory and runs the fastest but at the cost of some accuracy.

Advanced Subsectioning Options

Clicking on the Show Secondary button on the Sonnet tab of the Options dialog box displays the Advanced Subsectioning options. The Advanced Subsectioning options are divided into two groups: Sonnet Native Options and All Polygon Meshing (MWO to Sonnet).

Analysis Speed/Memory Control


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Since subsectioning has a direct effect on processing time and accuracy, this al-lows the experienced user a measure of control over the trade off between them.

! WARNINGBe aware that these are advanced options and should not be changed from their default values except by an experienced user who understands the effects of these options.

The first section of Advanced Subsectioning Options is the Sonnet Native Options as pictured below.

Maximum Subsection Size: Sonnet’s analysis engine, em, uses a variable sub-section size. Small subsections are used where needed, such as around corners, and larger subsections are used elsewhere. This reduces the size of the matrix which must be inverted, often providing a dramatic increase in the speed of an analysis. In no case are the subsections smaller than a single cell.

Selecting the Enable Maximum Subsection size checkbox enables this option and the Maximum Subsection Size entry is displayed. This field allows you to limit the maximum size of the subsection, generated by the analysis engine, in terms of subsections per wavelength. The default of 20, used when this option is not on, is fine for most work and means that the maximum size of a subsection is 20 degrees at the highest frequency of analysis. Increasing this number decreases the maxi-mum subsection size until the limit of 1 subsection = 1 cell is reached.

SonnetNativeOptions


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Estimated Epsilon Effective: Normally, em has an algorithm which estimates the effective dielectric constant used to determine the wavelength used for maxi-mum subsection size. If the Enable Epsilon Effective checkbox is selected you may override the automatic algorithm and force em to use your dielectric constant, entered in the Estimated Epsilon Effective entry which appears, to calculate the wavelength which is used in setting the Maximum Subsection size. If this option is not on, then em is using its algorithm to determine the subsectioning frequency.

Polygon Edge Checking: Normally em considers one adjacent metal level in either direction from the present level when computing the subsectioning. This is an important consideration when thin dielectric layers are used. Polygon Edge Checking allows you to override the automatic algorithm and specify how many adjacent levels or Technology Layers should be considered when calculating sub-sections. You select the type of edge checking you wish to use, Level or Technol-ogy Layer, from the drop list which is enabled when you select this checkbox. Note that entering a value of zero causes em to only look at the present metal level.

• Level: If you select level, then the number of levels you enter are checked in either direction. For example, as shown below, if polygon edge checking is set to 2, then using level 6 as the reference level, levels 6-4 would interact in the upward direction and levels 6-8 in the downward direction.

• Technology Layers: If you select Tech Layers, then the number of adjacent Technology Layers you enter is checked in either direction. Metal levels which do not use Technology Layers are not included in the count but if a metal level is in between levels with Technology Layers, then polygon edge checking is done on that metal level as well.


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For example, as shown below, polygon edge checking is set to 2. Using Level 6 as the reference level, Technology Layer C and Technology Layer A (metal levels 6-1) interact and Technology Layer C and Technology Layer E (metal levels 6-9) interact.

Choose Subsection Frequency based on: The analysis engine, em, uses the subsectioning frequency to calculate the wavelength which is used in setting the Maximum subsection size. The subsectioning frequency is determined by the ra-dio buttons described below:

• Present and Previous Analyses: This is the default setting for the sub-sectioning frequency. Select this option if you wish to analyze your project at the highest frequency used in this or any previous run of the project.

• Present Analysis Only: In this case, the highest frequency at which the project is analyzed for this run is used to subsection the circuit.

• Previous Analyses Only: Select this option if you wish to analyze your project in a different frequency range than a previous run but wish to use the same subsectioning on your circuit. The maximum frequency from all previ-ous runs on this project will be used as the subsectioning frequency.

• Use Fixed Frequency: Select this option to enter the frequency you wish to use for the subsectioning frequency. Enter the desired frequency in the Choose Subsection Frequency entry line below. This frequency will be used as the subsectioning frequency for all analyses of this project.


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The second section of Advanced Subsectioning Options is the All Polygon Mesh-ing (MWO to Sonnet) as pictured below.

XMin, XMax, YMin, YMax: Sonnet allows you to control how cells are com-bined into subsections for each polygon. This is done using the parameters “X min”, “Y min”, “X max” and “Y max.” When you select the checkbox for one of these entries, an entry appears below into which you may enter the desired value. These fields are applied as a global setting for all polygons. For a detailed discus-sion of these parameters and how they affect subsectioning in Sonnet, please refer to "Changing the Subsectioning of a Polygon" on page 35 of the Sonnet User’s Guide.

Use Edge Mesh: When using the Edge Mesh option, all Manhattan polygons (no diagonal edges) are treated as if they were non-Manhattan polygons. In other words, the edge subsections are always one cell wide regardless of X Min or Y Min. This field is applied as a global setting for all polygons. When used in con-junction with large X Min or Y Min values, this option can be very useful in re-ducing the number of subsections but still maintaining the edge singularity. This is very often a good compromise between accuracy and speed. To enable Edge Mesh, select the Edge Mesh checkbox, then select “Yes” for the Edge Mesh Value entry which appears below.

All Metal Fill Type: This field allows you to set the fill type for all metal poly-gons in the translated project. If you do not wish to set a global fill type, select “<off>” from the drop list. If you wish to set a fill type, choose from Staircase, Diagonal or Conformal. For more information on fill types in Sonnet, please see “Default Subsectioning of a Polygon,” page 35 in the Sonnet User’s Guide.

All PolygonMeshing(MWO toSonnet)


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All Via Fill: This field allows you to set the fill method for all vias in your trans-lated project. If you do not wish to set a global fill method, select “<off>” from the drop list. If you wish to set a fill method, choose from Full, Ring, Vertices, Center, or Bar. For more information on via fill methods, please see "Meshing Fill for Vias" on page 290 of the Sonnet User’s Guide.

Conformal Mesh Subsection Length: You may set a maximum length for a conformal section by selecting this checkbox and entering the desired length in the entry line which appears below. This is useful in reducing the size of your confor-mal sections to ensure higher accuracy. The default length of a conformal section is 1/20 of the wavelength of the subsectioning frequency.

Executing the Analysis

When you select Simulate Analyze from the main menu of the Microwave Of-fice window, Sonnet will be launched to analyze the EM Structure. A progress window detailing the Sonnet analysis appears on your display.

The window closes when the simulation is complete unless the “Keep this window open when finished” checkbox is selected. Since this is an “Async” type of simu-lation, Microwave Office is not locked while the Sonnet simulation is running. However, any changes made in the EM Structure are not reflected in the presently running simulation. You must run another simulation to obtain results for the changed design.

../Dialog_Boxes/analysis_-_advanced_subsect.htm

../Dialog_Boxes/analysis_-_advanced_subsect.htm


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Solver Information

There is a Data Set properties dialog box which allows you to view Sonnet simu-lator information in a text file. This includes simulation information such as mem-ory use, analysis frequencies, de-embedding information, analysis time, licensing information, thread count and simulation results. There is also a simulation log file available.

You access the Data Set Properties dialog box in the following manner:

1 Right-click on the Information entry under the desired EM Structure and select Edit from the pop-up menu which appears.

The Data Set Properties dialog box appears on your display. You may also double-click on the Information entry to open the dialog box.


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2 Click on the Sim Info tab in the dialog box.

This tab allows you to access such simulator information as licensing information, memory requirements and other circuit information. Note that you may copy the information in this window into a text file by selecting the desired text in the window, then pressing CTRL+C.

3 To view the simulation log, click on the Sim Log tab in the Data Set Properties window.

The contents of the simulation log file is displayed in the output window.

Estimate Memory

Sonnet has an Estimate Memory command that allows you to subsection your cir-cuit before analysis and obtain memory estimates for your analysis. To run the Es-timate Memory command, do the following:

Sim LogTab


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1 Before you run an analysis, double-click on the Information entry under the desired EM Structure.

Sonnet is evoked to run the Estimate Memory command. The Simulation window appears to display the progress.


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When the subsectioning is complete, the memory use estimate and the subsection-ing information, listed by level and total amounts, appears in the Data Set Proper-ties dialog box. You may select the output and copy it to your clipboard.

View Response Data

You may open Sonnet’s response viewer in order to view the response data for your EM structure. The response viewer is the plotting tool. This program allows you to plot your response data as a Cartesian graph or a Smith chart. You may also plot the results of an equation. In addition, the response viewer may generate Spice lumped models.

To open Sonnet’s response viewer do the following.


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1 Right-click on the desired EM structure in the directory tree, and select “Open in Native Editor” from the pop-up menu which appears.

The translated Sonnet project is opened in Sonnet’s project editor.

EM Structure

Pop-upmenu

ProjectEditor


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2 Select Project View Response New Graph from the main menu of Sonnet’s project editor.

Sonnets’ response viewer is opened and displays the response data from your EM simulation. If this is the first time the response viewer has been opened, the default plot of DB[S11] is displayed.

For more information on using the response viewer, please refer to help in the pro-gram or the tutorials in the Sonnet’s Getting Started manual.

View Current Density Data

You may open Sonnet’s current density viewer in order to view the current density data for your EM structure. Current density data is only created if the run option to compute current density data is selected. See "Computing Current Density" on page 39 for instructions on selecting this option. You open Sonnet’s current den-sity viewer by following the instructions for opening Sonnet’s response viewer (see “View Response Data,” page 60) but select Project View Currents from the project editor main menu.

This launches Sonnet’s current density viewer; a visualization tool which acts as a post-processor providing you with an immediate qualitative view of the electro-magnetic interactions occurring within your circuit. The currents may also be dis-


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played in 3D as well as being animated as a function of frequency or time. For more information on using the current density viewer, please refer to help in the program or the tutorials in the Sonnet’s Getting Started manual.

Open Sonnet Task Bar

You may also open Sonnet’s task bar from Sonnet’s project editor main menu. You open Sonnet’s Task Bar by following the instructions for opening Sonnet’s response viewer (see “View Response Data,” page 60) but select Project Task Bar from the project editor main menu. The Sonnet task bar allows you to access all Sonnet applications, documentation and administrative functions.

View Far Field

You may open Sonnet’s far field viewer in order to view the far field radiation patterns for your EM structure. The far field viewer uses current density data to calculate its plots. Current density data is only created if the run option to compute


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current density data is selected. See "Computing Current Density" on page 39 for instructions on selecting this option. You open Sonnet’s far field viewer by following the instructions for opening Sonnet’s response viewer (see “View Response Data,” page 60) but select Project View Far Field from the project editor main menu.

This launches Sonnet’s far field viewer which is the radiation pattern computation and display program. It computes the far-field radiation pattern of radiating structures (such as patch antennas) using the current density information from em and displays the far-field radiation patterns in one of three formats: Cartesian plot, polar plot or surface plot. For more information on using the far field viewer, please refer to help in the program.

Response Data

When you use Sonnet as your analysis engine, the only electromagnetic simula-tion data which may be viewed in Microwave Office is the port parameter data (S, Y, Z, ABCD, etc.). Meshing, current density plots, and far field radiation pattern plots are not available in Microwave Office. When you choose Sonnet as your simulation engine, the Animation menu in Microwave Office is disabled. Howev-er, all of Sonnet’s response viewers are accessible through the interface. You must use Sonnet to view currents or far-field radiation patterns. Please see “View Re-sponse Data,” page 60 for more information about viewing response data in Son-net.


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You may use the Graph function in Microwave Office to create plots of port pa-rameter data including equations which use this data.

To view current density plots or far field radiation patterns, you must calculate current density data in your analysis. Since the format of current density data dif-fers in Microwave Office and Sonnet, you must use Sonnet modules to view the current density data produced by Sonnet. See “Viewing the Current Density Data” on page 40.

Sonnet also uses current density data to calculate far field radiation patterns. If you have created current density data in a Sonnet analysis, you may use Sonnet’s far field viewer to plot the patterns. To open Sonnet’s far field viewer, open the EM Structure in the Native Editor, Sonnet’s project editor, once the analysis is com-plete. Then, select Project View Far Field from the project editor’s main menu. Refer to online help for this program for instructions on how to view your data.

Working Outside Microwave Office

You may wish to run your EM simulation in the Sonnet environment to take ad-vantage of features not available in the NI AWR MWOffice Interface. To do so, you export your EM structure to Sonnet, make any desired changes in Sonnet’s project editor, and run the analysis. When the analysis is complete, you can use a specified response file to import the EM response data back into NI AWR MWOf-fice.

NOTE: Note that any changes made in Sonnet’s project editor will not be reflected in Microwave Office.

Exporting Your EM Structure to Sonnet

Export your EM Structure to a Sonnet project by doing the following:

1 Open your EM Structure in the Native Editor.

Your EM Structure is opened in Sonnet’s project editor. Microwave Office is locked until the project editor is closed.

2 Select File Save As from the main menu of the Sonnet project editor.

A browse window appears.


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3 Select a name and location for the Sonnet project you are creating from your EM Structure.

Your EM Structure is saved as a Sonnet project at the specified location.

You would then edit and analyze your circuit in Sonnet until the circuit satisfies your design criteria. Once this is completed, you can import the resulting data file into NI AWR Microwave Office.

Translation Issues

There are features in both Microwave Office and Sonnet which do not translate and several translation issues you should be aware of before using the NI AWR Microwave Office Interface. These are all discussed in the sections following.

Sonnet Features Not Available in NI AWR MWOffice Interface

These features are handled differently depending whether you are using Micro-wave Office to edit your EM Structure or Sonnet’s project editor (Native Editor). The table below lists the Sonnet features not available in Microwave Office and how the feature is handled with each editor.

! WARNINGWhen a conversion or deletion occurs when you are editing in MicrowaveOffice, the change is permanent and is not restored if you open the EMStructure in the project editor.

Sonnet Feature Edit in Microwave Office Edit in Sonnet’s Project

Editor

Dimensions Deleted from geometry Kept in circuit but not dis-played in Microwave Office

Subdividers Deleted from geometry Kept in circuit but not dis-played in Microwave Office

Parameters Deleted from geometry Kept in circuit but not dis-played in Microwave Office


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Parallel Subsections Deleted from geometry Kept in circuit but not dis-played in Microwave Office

Linked Reference Planes Converted to a fixed length reference plane

Displayed in Microwave Of-fice as fixed length reference planes

Calibration Lengths Deleted from geometry Kept in circuit but not dis-played in Microwave Office

Edge Vias Deleted from geometry Kept in circuit but not dis-played in Microwave Office

Dielectric Bricks Deleted from geometry Kept in circuit but not dis-played in Microwave Office

Capacitance and Inductance in Port definitions

Capacitance and Inductance set equal to 0

Kept in circuit but not dis-played in Microwave Office

Inductance (Ls) for metals Set to a value of zero. Kept in circuit but not dis-played in Microwave Office

Comments Deleted from geometry Kept in circuit but not avail-able in Microwave Office

Metal Types See "Metal Types" on page 68 See "Metal Types" on page 68

Port Mapping See "Port Mapping" on page 68

See "Port Mapping" on page 68

Components or co-calibrated Ports

Deleted from geometry Kept in circuit but not avail-able in Microwave Office

Ports on Ground Plane See "Ports on Ground Plane" on page 70

See "Ports on Ground Plane" on page 70

Port Termination and Excita-tion

See "Port Termination and Excitation" on page 70

See "Port Termination and Excitation" on page 70

Off Grid Placement See "Coordinate System" on page 71

See "Coordinate System" on page 71

Coordinate System See "Coordinate System" on page 71

See "Coordinate System" on page 71

Sonnet Feature Edit in Microwave Office Edit in Sonnet’s Project

Editor


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Metal Types

There are seven different metal type models available in Sonnet: Normal, Resis-tor, Rdc/Rrf, General, Sense Metal, Rough Metal and Thick Metal Model. NI AWR MWOffice only supports the Normal metal type. If you wish to use another metal type, you must edit and analyze in the Sonnet Environment.

Modeling Thick Metal

If you wish to define a metal type using Sonnet’s thick metal type, you may do so by following a naming convention in Microwave Office as follows:

SonThick< Metal Name>

Where “SonThick” identifies this as a thick metal, and the < Metal Name> is the type of metal. For example, if you wished to define a thick metal copper modeled using two sheets, the name would be:

SonThick_Copper

Note that the model defaults to using two sheets.

Port Mapping

Microwave Office only allows consecutive numbering for ports starting at the val-ue of one. The port number must be a positive integer. Sonnet allows you to have duplicate port numbers and allows you to use negative port numbers. Sonnet’s analysis engine, em, sums the total current going into all the positive ports with the same port number and sets that equal to the total current going out of all the ports with that same negative port number.

When the EM Structure is sent to Sonnet from Microwave Office, Sonnet uses the port numbers sent by Microwave Office. If you wish to take advantage of using negative port numbers, you must edit and analyze in the Sonnet environment.

Co-calibrated Port

You may enter ports in Microwave Office that are automatically converted to co-calibrated ports in the Sonnet environment. To do so, you must add an internal port connected only to a single open ended polygon. This is normally an error condi-tion, but in the interface it is being used to translate co-calibrated ports directly


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from Microwave Office to the Sonnet environment without the need of editing your geometry in Sonnet. The illustration below shows the appearance of the port in Microwave Office on the left and the translated port shown in the Sonnet project editor.

When entering the internal port in Microwave Office, you should ignore the po-larity displayed in Microwave office when entering these ports. Microwave Office always shows the negative (-) terminal inside the polygon and the positive (+) ter-minal outside the polygon. When this type of port is translated into the Sonnet en-vironment, the port number will always be positive and this means the positive (+) terminal will be connected to the polygon and the negative (-) terminal is connect-ed to ground. This will always be the case when translating the internal port on an open edge of a polygon from Microwave Office to a co-calibrated port in Sonnet.

Ports as they appear in Microwave Office.

The translated ports shown as co-calibrated ports in Sonnet’s project editor


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Via-Ports

During the EM extraction, Sonnet converts via ports in Microwave Office to either standard, auto-grounded or co-calibrated ports depending upon the setting of Port Conversion Options for Open Ended Ports. If co-calibrated ports are created, then the ports are automatically grouped by the analysis engine in Sonnet. An example is shown below.

Ports on Ground Plane

Sonnet allows you to place a port on the ground plane; this is an error condition in Microwave Office which prevents an analysis from being executed. A port on the ground plane in Microwave Office is translated into a via port which extends from the ground plane (substrate) up to the level above.

Port Termination and Excitation

A port may be defined in two ways in Microwave Office: termination and excita-tion. You define the termination of a port as the real and imaginary parts. This translates directly into Sonnet as the Resistance and Reactance parameter of the port. Microwave Office does not allow you to define the Inductance or Capaci-tance of a port, unlike Sonnet.

Via ports in Microwave Office Co-calibrated ports in Sonnet’s project editor.


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Microwave Office allows you to define the excitation of one port in your circuit by entering the Available Power and Phase. Sonnet does not have the ability to de-fine port excitation in the project editor. Therefore, if an EM Structure is translated into Sonnet, these values are deleted for the port and the termination definition is used.

Sonnet does provide port excitation in both the current density viewer and the far field viewer. For details, see online help for either program.

Coordinate System

Microwave Office and Sonnet use different coordinate systems. The origin (0,0) in Sonnet is the lower left hand corner of the substrate while the origin in Micro-wave Office is the upper left hand corner of the substrate which Microwave Office refers to as the ground plane. See "Errors in the Coordinate System" on page 72 for more information.

3D Viewer Scaling

Microwave Office’s 3D viewer has a scale setting for the dielectric layers which allows you to display a dielectric layer larger than it is relative to the other dielec-tric layers. If you open the EM Structure in Sonnet there exists no way to specify the 3D viewer scaling.

Meshing, Current Density Plots and Far Field Plots

When you use Sonnet as your analysis engine, you may not view meshing, current density plots or far field radiation plots in Microwave Office. The Animation menu in Microwave Office is disabled when Sonnet is selected as your analysis engine. For details on viewing this data in Sonnet, see "Response Data" on page 64.


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Troubleshooting

Errors in the Coordinate System

Microwave Office and Sonnet use different coordinate systems. The origin (0,0) in Sonnet is the lower left hand corner of the substrate while the origin in Micro-wave Office is the upper left hand corner of the substrate which Microwave Office refers to as the ground plane. This fact is important to remember if you receive er-ror messages which specify a grid position. Error messages from Sonnet are based on Sonnet coordinates and may need to be converted to Microwave Office coor-dinates to effectively diagnose the source of the error.

Chapter 3 NI AWR Microwave Office Interface Tutorial

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Introduction

Sonnet has taken advantage of this opportunity by creating the NI AWR Micro-wave Office Interface (MOI) 64 Bit which allows for the seamless incorporation of Sonnet’s world class EM simulation engine, em, into the Microwave Office 13 or higher environment. You can take advantage of Sonnet’s accuracy without hav-ing to learn the Sonnet interface. Although, for advanced users who wish to take advantage of powerful advanced features not presently supported in the integrated environment, the partnership of NI AWR and Sonnet has simplified the process of moving EM projects from Microwave Office to Sonnet.

For a detailed discussion of the NI AWR Microwave Office Interface 64 Bit, its modes of operation and translation issues, please see Chapter 2 "NI AWR Micro-wave Office Interface 64 Bit" on page 15.

The NI AWR Microwave Office Interface (MOI) 64 Bit tutorial is designed to give you a brief overview of the interface between Sonnet and NI AWR’s Microwave Office. This tutorial assumes that you are familiar with the basics of using both Sonnet and Microwave Office. If this is not true, we recommend


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referring to the appropriate documentation. If you are new to Sonnet, we suggest performing the tutorials in the Sonnet Getting Started manual available in PDF format through the Sonnet task bar before using this tutorial.

Tutorial Topics

The following topics are covered in this tutorial:

• Editing in Microwave Office, editing in Sonnet, and working out-side of Microwave office.

• Opening Sonnet’s project editor from within Microwave Office.

• Setting up an Adaptive Band Synthesis sweep for the Sonnet analy-sis engine.

• Running a simple analysis in Microwave Office using Sonnet’s analysis engine, em.

• Observing response data in both Microwave Office and Sonnet.

• Exporting an EM structure from Microwave Office to a Sonnet project.

Obtaining the Example Project

The Microwave Office example project for this tutorial is supplied with your Sonnet software installation and is available through the Sonnet Example Browser You may access the Sonnet Example browser by selecting Help Browse


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Examples from the menu of any Sonnet application. For instructions on using the Example Browser, please click on the Help button in the Example Browser window. Save the example “lowpass_64” to your working directory.

“lowpass_64” example

NI AWRMicrowaveOffice examples


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1 Open the NI AWR Design Environment.

Microwave Office is invoked on your display without an open project. It should appear similar to the picture shown below.

2 Select File Open Project from the Microwave Office main menu.

The browse window appears. Navigate to the directory in which you saved the lowpass example and select the file “lowpass_64.emp.”

ProjectBrowserwindow


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A query box similar to that shown below may appear. This appears if you have both the 32-bit and 64-bit version of the interface installed, or are attempting to open a project created with the 32-bit interface in the 64-bit interface. The name being used for Sonnet has changed between the versions.

! WARNINGThe name of the Sonnet simulator is different in the 32-bit and 64-bit interfaces. This message indicates that the software is attempting to access the 32-bit simulator. It is imperative that you answer “No” in the query box. You will select the correct, 64-bit, analysis engine later.

3 Click on “No” to close the query box.

The project file is opened with nothing displayed but the Project Browser window is updated.

3 Stagelow PassFilter

Low PassFilter


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4 Double-click on “3 Stage Low Pass Filter” under Circuit Schematics in the project browser window.

This circuit uses the EM structure “Low Pass Filter” by connecting together three of the structures.

5 Double-click on the EM structure “Low Pass Filter” in the project browser window.

The Low Pass Filter circuit is opened in a layout window. This is the EM structure used in the schematic. Note that the presently active display is indicated by the highlighted title bar and color tab.

EmStructureLow PassFilter


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6 Select View View 3D EM Layout from the Microwave Office main menu.

A 3-dimensional view of the EM structure appears in the Microwave Office window.

7 Double-click on “EM Lowpass Filter Response” under Graphs in the project browser window.

The graph appears in the Microwave Office window. Note that the graph is empty since no analysis has yet been run on your Microwave Office project.


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8 Select Window Tile Vertical from the Microwave Office main menu.

This command makes all four open windows the same size and fills all the space available. Your display should now appear similar to the picture shown below. The order in which the views are displayed may vary.

Editing in Microwave Office

You must use Microwave Office to edit your EM structure if you wish to keep the EM structure in Microwave Office synced with the translated Sonnet project. You can choose to edit the EM structure in the Native Editor (Sonnet’s project editor), but any changes made to the project will not be reflected in the EM Structure. You can perform your analysis in the Sonnet environment, then import the resulting data file into Microwave Office.

When using Microwave Office to edit your structure, you remain in the Micro-wave Office environment, editing your EM structures and controlling Sonnet analysis options using options available in Microwave Office. The Sonnet analy-sis engine, em, is invoked from Microwave Office and the analysis results dis-


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played in Microwave Office and, optionally, in Sonnet. This section of the tutorial will demonstrate how to select Sonnet as your analysis engine, how to setup the analysis in Microwave Office, how to execute the analysis and how to observe analysis results all from within the NI AWR Microwave Office environment.

TIP

The Sonnet analysis engine must be selected for each EM structure in the Micro-wave Office project.

Selecting Sonnet as your EM Analysis Engine

1 Right-click on the EM Structure “Low Pass Filter” in the Project Browser section of the Microwave Office window as shown below.

A pop-up menu appears on your display.

EM structureLow Pass Filter


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2 Select “Set Simulator” from the pop-up menu.

The Select a Simulator dialog box appears on your display.

3 Click on the “Sonnet Simulator 3D Planar - Async” radio button.

This selects em, Sonnet’s electromagnetic simulator engine, as the engine to use when performing analyses on the Low Pass Filter structure in Microwave Office.

NOTE: If more than one Sonnet entry appears, please select the one ending in “Async.”


Selecting Analysis Controls

Sonnet provides analysis controls within the Microwave Office environment for Sonnet’s em. To view and/or set these controls, do the following:

Sonnetradiobutton


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5 Right-click on the EM Structure “Low Pass Filter” in the Project Browser section of the Microwave Office window as shown below.

A pop-up menu appears on your display.

6 Select “Options” from the pop-up menu.

The Options dialog box appears on your display with the General Tab selected.

7 Click on the “Sonnet” tab in the Options dialog box.

The appearance of the dialog box changes and should appear similar to the picture shown below.

The ABS sweep across the full band is already set up by default, so you will need to take no action to setup the ABS sweep for Sonnet.

EM structureLow Pass Filter

UseAdaptiveBandSynthesisCheckbox

ABSBand Selection


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The Adaptive Sweep Settings control allows you to specify whether or not you want adaptive processing to be used when generating the S-parameter results. In Sonnet, the adaptive technique is called Adaptive Band Synthesis (ABS). If you disable Use Adaptive Band Synthesis, the analysis engine analyzes the circuit at each frequency specified in Microwave Office. This is recommended if you have fewer than five frequencies requested by Microwave Office.

If, however, you specified five, or more, frequencies in Microwave Office, then it is usually more efficient to enable Use Adaptive Band Synthesis. When enabled, the analysis engine does an ABS sweep over the specified frequency band first, and then it uses the adaptive results to generate S-parameters at each of the Micro-wave Office frequencies. This allows you to specify a very fine frequency resolu-tion in Microwave Office, with hundreds or even thousands of individual frequencies, and obtain those results in the same time it would take to compute 5-10 frequencies without adaptive processing.

The Global project analysis frequencies for this Microwave Office project are from 5 to 35 GHz in 0.2 GHz steps. In this case, the default setting for Sonnet, full-band ABS, is the most efficient choice.

8 Scroll down to the Project Options section and click on the Compute Currents checkbox to select this run option.

You check the Compute Currents control to enable generation of current density information when the analysis engine runs. By default, current density informa-tion is not generated. When you select this option, the View Currents button in the Solver Information dialog box is enabled at the end of the analysis. Later in the tutorial, you use this button to launch the Sonnet Current Density Viewer.

ProjectOptionsSection

ComputeCurrentscheckbox

ShowSecondarybutton


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There are other advanced run options available by clicking on the Show Second-ary button in the Options dialog box. For more information about Advanced Proj-ect Options, see “Advanced Project Options,” page 43.


Running the Simulation

When you invoke a simulation, Microwave Office sends the geometry informa-tion of the EM structure to Sonnet along with the analysis controls. When the EM simulation is complete, Sonnet returns the requested analysis data.

To run the simulation, do the following:

10 Select Simulate Analyze from the main menu of Microwave Office.

A status window indicating the progress of the EM simulation being performed by the Sonnet analysis engine, em, appears on your display as shown below. Depending on your computer, the EM analysis may take a few minutes to complete.

Once the simulation of the EM structure is complete, the status window is closed unless the Keep this window open when finished checkbox is selected (as shown above). The analysis of the complete circuit in the Microwave Office project is


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completed very quickly. You may now observe the results. Please note again that although Sonnet produced approximately 300 data points as the result of the ABS sweep, it returned data for only the 61 data points requested by Microwave Office.

During an ABS sweep, em analyzes at the beginning and end of the desired fre-quency band. Using an iterative process, em then analyzes at other discrete fre-quencies and determines a rational polynomial fit to the S-parameter data within the frequency band. The data produced by the full analysis at specific frequency points is the discrete data. Once a rational polynomial fit is achieved with an ac-ceptable error, the frequency response across the specified bandwidth is calculat-ed. The data generated using the rational polynomial is the adaptive data. For this particular ABS sweep, em performed a full analysis at 6 frequency points.

The S-parameter data returned from Sonnet to Microwave Office may be plotted using the graph capability in Microwave Office. For your convenience, a graph has already been set up in the example project.

11 If the graph is not already displayed in Microwave Office, double-click on EM Low Pass Filter Response under Graphs in the Project Browser.

The plot should appear similar to the one pictured below. This plot shows the response of the EM structure Low Pass Filter.

Microwave Office Plot


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12 To view the response of the whole circuit in the schematic, 3 Stage Low Pass Filter, click on “3 Stage Low Pass Filter Response” under Graphs in the Project Browser.

This plot shows the response of the whole circuit.

It is not possible at this time to display the current density data created by Sonnet within the Microwave Office environment, but you may invoke Sonnet’s current density viewer by opening your EM structure in Sonnet’s project viewer.

13 Right-click on the “Low Pass Filter” entry in the Project Browser window.

A pop-up menu appears.

Lowpass Filter

Open inNative Editor


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14 Select “Open in Native Editor” in the pop-up menu.

Sonnet’s project editor is opened displaying the translated EM structure.

15 Select Project View Currents from the main menu of Sonnet’s project editor.

The current density viewer appears on your display.If you try to open a project which does not contain .jxy data, an error message is displayed.

Project menu


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16 Click on the Down Level button to view the lower metal level.

Level 1 of Low Pass Filter.son is displayed for the frequency 5 GHz.

The default animation setup for the current density viewer is to animate as a func-tion of frequency, so it is a simple operation to view the change in current density in your structure as a function of frequency. It is important to note that current den-sity data only exists for the six discrete data points where a full analysis was done. The adaptive data does not include current density data.

TIP

For more details on using the current density viewer in Sonnet please refer to Chapter 4 "Tutorial: A Quick Tour" on page 37 in the Getting Started manual and to online help for the current density viewer.

17 Select File Exit from the current density viewer main menu.

This exits the current density viewer. During the normal design process, observing the response data may lead to making changes in the EM structure. You would edit the EM structure in Microwave Office before once again simulating the circuit.

18 Select File Exit from the project editor main menu.

This exists the project editor.

The next section of this tutorial discusses using the native editor in the NI AWR Microwave Office Interface in which you use the Sonnet project editor to edit your EM structure.


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Native Editor

If you choose the native editor, Sonnet’s project editor, you not only use Sonnet as your electromagnetic simulator but also the EM structure editor. The native ed-itor allows you to take advantage of all the capabilities unique to Sonnet including variables, dielectric bricks, diagonal ports, etc. Using the native editor requires that you are already conversant with Sonnet software or will have to use Sonnet documentation to gain familiarity with the Sonnet environment.

Any changes made in Sonnet’s project editor are not reflected in the EM structure in NI AWR Microwave Office. When you run a simulation from within Micro-wave Office, the EM structure is translated and deletes any changes made in the Sonnet Environment; therefore, if you edit your EM structure in Sonnet, the anal-ysis should be run in Sonnet and the resulting data file imported into Microwave Office and swapped out in the schematic for the EM structure. This next section of the tutorial demonstrates this process.

For this tutorial, you will define a variable to be used in a dimension parameter in Sonnet and then run a parameter sweep to determine the best length for your de-sign. Variables are a feature not available with a Microwave Office EM structure and will be used to demonstrate using Sonnet’s project editor as the native editor.

Once the circuit has been parameterized, and analysis results have been created using a parameter sweep, it is possible to specify the nominal value in Sonnet in order to create final design analysis results. The resulting data file can then be im-ported into NI AWR Microwave Office and swapped out for the EM structure in your schematic.


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Editing your EM Structure in Sonnet

19 Right click on Low Pass Filter in the project browser window in Microwave Office and select “Open in Native Editor” from the pop-up menu.

Sonnet’s project editor appears on your display with the EM structure Low Pass Filter open displaying the top most metal level 0.

20 Click on the Down One Level button on the project editor tool bar.

Metal level 1 appears in the project editor’s window. You will add the dimension parameter on this level.

Adding Dimension Parameters

We will parameterize the length of the stubs shown below by creating an anchored dimension parameter using the variable “Length” to control the length of the stubs. The desired outcome is for the lowpass filter to pass the lowest frequency


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possible. The Parameter Sweep will vary the length from 170 microns to 220 mi-crons in steps of 10 microns. Once the parameter sweep is complete, the response data will be examined to determine which length yielded the lowest frequency.

In order to run a parameter sweep, a dimension parameter must be added to the stub length.

21 Select Tools Add Dimension Parameter Add Anchored from the project editor main menu.

The appearance of the cursor changes. An anchored dimension parameter extends from an anchor point which remains fixed to a reference point, whose position is changed based on the nominal value of the dimension parameter and the point set which maintains their relative positions to the reference point. As you are adding the dimension parameter, instructions appear in the project editor window for each step.

Stubs to beparameterized


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22 Click on the lower left hand corner of the stub to define the anchor point.

The point is highlighted with an open square, as shown below.

23 Click on the upper left hand corner of the stub to define the reference point.

The reference point is also highlighted with an open square. This point is moved when the nominal value of the dimension parameter is changed, while the anchor point remains fixed in place.

Anchorpoint

Next step

Referencepoint

Next step


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24 Select the upper right hand corner of the stub to add it to the point set.

You may do this by clicking on the point or by clicking and dragging a lasso to surround the point. The point is highlighted with a Fill square. This point is moved when the nominal value of the dimension parameter is changed but always main-tains its relative position to the Reference point. This is the only point that needs to be added in this case; the point set may contain as many points as you wish.

25 Press the Enter key to complete the entry of the point set.

The Parameter Properties dialog box appears on your display. This dialog box allows you to assign a variable to the dimension parameter. The nominal value is the existing length of the stub as it now appears in your circuit and is automatically filled in.

PointSet

Nametext entrybox


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26 Enter the name “Length” in the Name text entry box in the Parameter Properties dialog box, then click on the OK button to close the dialog box.

This assigns the variable “Length” to the dimension parameter. When you click on the OK button an arrow indicating the length and the name appear on your display.

27 Move the mouse until the name is positioned alongside the stub. When the name is in the desired position, click on the mouse.

The dimension parameter should now appear as shown below.

28 In a similar manner, add a dimension parameter using the same variable “Length” to the stub on the right side.

Once you have added the second dimension parameter, your circuit should appear similar to that shown below.

Dimension parameter “Length”

Note that the nominal length of 170 mils is displayed by default.

DimensionParameter

DimensionParameter


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This completes entering the dimension parameters. The next step is setting up the parameter sweep.

Parameter Sweep

29 Select Analysis Setup from the project editor main menu.

The Analysis Setup dialog box appears on your display with the Analysis Control set to “Adaptive Sweep (ABS)” and the frequency band set to 5.0 GHz to 35.0 GHz, which is the frequency band inherited from the EM structure.

30 Select “Parameter Sweep” from the Analysis Control drop list.

The appearance of the dialog box changes.

Addbutton


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31 Click on the Add button in the Analysis Setup dialog box.

The Parameter Sweep Entry dialog box appears on your display. You use this dialog box to define your parameter sweep.

The Adaptive Sweep from 5.0 to 35 GHz was set when the circuit was translated into Sonnet and does not need to be changed. The default of a Linear Sweep, which analyzes the circuit at every available parameter combination, is also ap-propriate for this analysis and does not need to be changed.

32 Click on the Length checkbox.

This selects the variable “Length” for the parameter sweep. This means that the value of “Length” is changed for each analysis according to the controls entered on this line. Once the variable is selected, the text entry boxes are enabled.


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33 Enter “170” in the Start text entry box, “220” in the Stop text entry box and “10” in the Step entry box.

As mentioned earlier, we wish to sweep the length from 170 microns to 220 microns in steps of 10 microns, so that six analyses are performed with the length set to 170, 180, 190, 200, 210 and 220 microns. Note that the present value of the variable, 170.0 microns appears in the Nominal column. The dialog box should appear as shown below.


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The parameter sweep entry now appears in the Analysis Setup dialog box.

35 Click on the OK button in the Analysis Setup dialog box.

A Multiple File Notice may appear on your display. If so, click on the OK button to close this notice.

36 Click on the Save button on the project editor tool bar to save your changes.

The project editor will prompt you to remove the analysis results stored in the project, since the changes made in the geometry make that data obsolete.


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37 Click on the Delete button to delete the inconsistent results.

38 Click on the Analyze button on the project editor tool bar to run the simulation.

The Analysis Monitor appears to show the progress of the analysis. Depending on your system and resources, it may take a few minutes for the analysis to complete. Once the analysis is complete, the progress bar in the analysis monitor is completely filled and “Analysis Completed” is displayed in the output window.

The next step is to view the response data to determine which length yielded the best results.

ViewResponsebutton


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Viewing the Response Data

39 Click on the View Response button on the Analysis Monitor tool bar.

The Sonnet Response Viewer appears on your display with a plot of the default DB[S11]

40 Double-click on the Low Pass Filter curve in the Left Axis curve group legend.

The Edit Curve Group dialog box appears on your display. To determine what length yielded the lowest frequency pass, plot the S11 and S21 measurements for all the parameter values.

41 Double click on DB[S21] in the Unselected list.

DB[S11] and DB[S21] now appear in the Selected list which will add the DB[S21] measurements to the plot.

Curve group legend


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42 Click on the Graph All Combinations checkbox in the Parameter Combinations section of the dialog box.

This will display the selected measurements at all the values of the variable “Length.” Notice that the list is updated with all the possible values.

Selected List

Graph All Combinationscheckbox

Parameter valuesbeing plotted


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The plot is updated with the selected data and should appear similar to the plot shown below.

44 Click on the lowest point of the S11 plot whose minimum occurs at the lowest frequency.

When you click on that point, the data curve is highlighted and a readout appears on the plot. The parameter value for this curve group is 220 microns which is the value you wish to use for the length of the stub.

45 Select File Exit from the response viewer main menu.

This closes the response viewer.


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46 Select File Exit from the analysis monitor main menu.

This closes the analysis monitor.

47 In the project editor window, double-click on the Length dimension parameter.

The Parameter Properties dialog box appears on your display.

48 Enter the value “220.0” in the Nominal text entry box.

This changes the length of the stub to 220 microns which was identified by the pa-rameter sweep as the optimal length for the design.


The plot is updated to reflect the new nominal length.

Nominal text entry box


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Next. you want to produce a data file for the circuit using 220 as the length of the stub.

50 Select Analysis Clean Data from the project editor main menu.

The Clean Project Data dialog box appears on your display. By deleting all the data, we can re-run the analysis using the new nominal value of 220 to produce an output file which contains only the data for that length. Note that separate output files were created for each parameter, but it may be difficult to identify which file you wish to use. This process ensures you are using the data for the correct geometry.

51 Click on the OK button in the Clean Project Data dialog box to delete the data.

Delete all data is the default setting so there is no need to make any changes in the dialog box.

52 Select Analysis Setup from the project editor main menu.

The Analysis Setup dialog box appears on your display with the parameter sweep still selected.


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53 Select “Adaptive Sweep (ABS)” from the Analysis Control drop list.

The appearance of the Analysis Setup dialog box is updated. The frequency band for the ABS sweep was saved and is correctly set.

Click on the OK button in the Analysis Setup dialog box to close the dialog box and apply the changes.

54 Click on the Save button in the project editor tool bar to save your changes.

This saves the project with the desired nominal value for the Length dimension parameter and the project contains no data. The analysis is set up to perform an adaptive sweep from 5.0 GHz to 35.0 GHz, the data we need for the EM structure in Microwave Office.

55 Click on the Analyze button on the project editor tool bar to run the simulation.

The Analysis Monitor appears again to show the progress of the analysis. Depending on your system and resources, it may take a few minutes for the analysis to complete. Once the analysis is complete, the progress bar in the analysis monitor is completely filled and “Analysis Completed” is displayed in the output window.

A Touchstone format response data file was specified when the EM Structure was translated into a Sonnet project and was automatically created at the end of your analysis. Select File Exit from the project editor main menu.

The project editor disappears from your display.


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Importing the Data File

Next, you need to import the response data file created by your analysis into NI AWR Microwave Office.

56 In the project tree in Microwave Office, right-click on the Data Files entry and select Import Data File from the pop-up menu which appears.

A Browse window is opened to allow you to select the file.

57 Select the response data file you just created.

This file may be found at:

<Example Location>\TEMP\lowpass_64\Low Pass%0.emi.s2p

where <Example Location> is the directory into which you copied the Lowpass_64 example at the beginning of the tutorial. When you select the file, a message box appears warning you of illegal characters in the data file’s name.

Data Files

Import Data File


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58 Click on OK in the message box to close it and import the file.

The project tree is updated and displays the response file, Low Pass Filter_0_emi, under Data Files. Next, we need to create a switch view which references the response file so we can specify the file in the schematic in place of the EM Structure.

59 Right-click on the File name and select “Add Switch View” from the pop-up menu.

The New Schematic dialog box appears on your display.

Imported responsedata file

Data File

Add Switch View


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60 Click on the “Create as a Linked File” checkbox in the New Schematic dialog box.

The View will link to the data file. There is a default name specified for the element.

61 Click on the Create button to create the switch view.

The View is created. If the dialog box remains open, you may close it by clicking on the “X” in the upper right hand corner.

62 Click on the 3 Stage Low Pass Filter schematic window which should still be open in Microwave Office.

We need to swap out the EM structures in the schematic for the data response file imported from Sonnet.

63 Right-click on the first symbol for the EM Structure in the schematic and select “Swap Element” from the pop-menu which appears.

The Swap Element dialog box appears on your display.

Low Pass FilterEM structure

Swap Element


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64 Select “Low Pass Filter_0_emi” from the list of elements.

The Element for the file should appear last in the list.

65 Click on the OK button in the Swap Element dialog box to close the dialog box and apply the changes.

The schematic is updated to display the response data file element in place of the EM Structure. Repeat the process for the other two EM structure symbols in the schematic. Once you have completed swapping all the elements, you are ready to analyze using the EM results from the Sonnet analysis.

NOTE: Another approach for this problem would be to edit the EM Structure in Microwave Office, changing the stub length to 220 and keep the Low Pass Filter EM structures in the schematic. However, for the purposes of this tutorial, we wished to demonstrate how to use the Sonnet results in the case of changes not possible to make when editing in Microwave Office.

Response data fileelement

Response Data File.


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Running the Simulation

66 In Microwave Office, select Simulate Analyze from the main menu.

A status window appears on your display indicating the progress of the circuit simulation. This analysis takes less time than the earlier analysis in Microwave Office, since the response data for the EM structure is already available from the imported response file so Sonnet is not evoked to run an EM simulation.

67 Double-click on “3 Stage Low Pass Filter Response” under Graphs in the Project Browser.

This plot shows the response of the whole circuit using the EM structure modified for the optimal stub length. The plot closely resembles the one from the beginning of the tutorial when the analysis is run from Microwave Office and the stub length in the EM structure was 170. This response is for the adjusted stub length of 220. Being able to analyze in Sonnet’s native environment allowed you to determine the best stub length, then utilize those results in your circuit simulation in Microwave Office.

This completes the NI AWR Microwave Office Interface tutorial.


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Appendix I Via Simplification

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Introduction

Several manufacturing processes used to produce RF circuits utilize via arrays or bar via groups to provide the trace metal layer to layer connections. Both of these types of vias present an analysis challenge which drives the Sonnet model memory and analysis time requirements beyond what is practical to analyze. Via simplifi-cation provides an approach to via arrays and bar vias that reduce the time and memory requirements without sacrificing accuracy. These two processes are dis-cussed in this appendix.

Via Array Simplification

For via arrays, the small size of the individual vias and the large number in the ar-ray usually drive Sonnet model memory and analysis time requirements beyond what is practical to analyze. This often requires that you simplify the via geometry detail before performing your EM simulation. In the past, via array simplification would need to be done manually by deleting vias and replacing with a single, larg-er via polygon.


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The Simplify Via Array feature automatically performs this simplification during the translation process. It can be invoked inside the Keysight ADS Interface, the Cadence Virtuoso Interface, NI AWR Microwave Office Interface - 32 Bit and NI AWR Microwave Office Interface - 64 Bit. It may also be invoked in Sonnet’s project editor when performing an import using the Gerber/ODB++ Translator, GDSII Translator or DXF Translator.

Via Array Criteria

There are six criteria, all of which must be met, before a group of vias in the orig-inal geometry is considered an array and therefore simplified by the software.

Number of Vias: There must be a minimum number of vias in order for them to be considered an array.

Via Size: The vias must be the same size or nearly the same size.

Via Spacing: The vias must be within a certain distance of one another.

Layer Pass Through: The vias must pass through the same layer(s).

Metal Polygons Pads: The vias must be contained within the same metal poly-gon at either the top or the bottom of the vias.

Material: The vias must be set to the same material, whose conductivity is the same.

Additional Simplify Via Array Options

This text entry box should only be used at the direction of a Sonnet representative.

Simplify Via Array Options

There are six control options for the simplify via array feature which are discussed in detail in the following sections. We will use a simple example circuit to illus-trate how the options affect the via simplification.


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TIP

The default values were determined based on extensive testing, and in the majority of cases will provide reasonable via simplification behavior. However, Sonnet handles a wide range of layouts and processes, so these controls were provided so that a user can customize the translation if it proves necessary.

The example structure consists of three metal layers and two interconnecting via arrays, as shown below. Since the vias pass through different dielectric layers and use different metal types, the 1 X 2 array and the 5 X 5 array would never be grouped together. Either reason would be sufficient on its own to prevent these two arrays being grouped together.

3D View of circuit

2D View of Metal Level 1

The 5 X 5 via array extends from metal level 1 to metal level 2 through the lower dielectric layer.

The 1 X 2 via array extends from metal level 0 to metal level 1 through the upper dielectric layer.

1 X 2 via array. Each via is 1 μm square and the assigned metal type is Via1.

5 X 5 via array. Each via is 4 μm square and the assigned metal type is Via2.


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Minimum Vias in Array

This control defines the minimum number of vias which can be considered part of the same array. The default value for this setting is 5, so that only arrays with 5 or more vias will be considered for simplification. Therefore, in our example the 1 x 2 via array would not be simplified, but the 5 X 5 would be analyzed to see if this array meets the rest of the simplification criteria. You may enter any integer value to set the minimum number required.

Max Distance to Size Ratio

This control defines the maximum spacing between vias which can be considered part of the same array. While the distance between vias is measured from the cen-ter lines of the individual vias, the control is a ratio of distance to via size. This distance cannot exceed the value of this ratio multiplied by the via size. The de-fault setting is 4.0 and the larger the value, the more widespread the vias can be and still be grouped in the same array. Since individual via cross-sections can be of any shape, the square root of the via area is used as the via size.

1 X 2 Via arrayWill not be simplified

5 X 5 Via ArrayWill be simplified


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For our example the size of the vias is 2.0 μm and the center to center spacing is 4.0 μm, as pictured below. This results in a Distance to Size ratio of 4.0/2.0 = 2.0 so that this array meets the via spacing criteria.

Maximum Size to Size Ratio

This control defines the maximum allowable difference in via size to be consid-ered part of the same array. The default value of this ratio is 1.5 and the larger the value, the greater the difference of via size is allowed within an array. Since indi-vidual via cross-sections can be of any shape, the square root of the via area is used as the via size. For this example, the via cross-section is a 2.0 X 2.0 μm square. The area is 4 μm2 and taking the square root, yields a via size value of 2 μm.

Since all of the vias are the same size in this array (2.0 μm) the Size to Size ratio is 1.0, so that this array meets the via size criteria.

TIPIf you wish to limit your arrays to vias of the same size, set this control to 1.0.

Max Expansion Coefficient

This control helps define the size of the resulting simplified via by allowing it to be larger than the original via array perimeter (also referred to as the bounding box). The default value is 7.0, which allows the simplified via to expand outward by a factor of 7 times the largest via size in the array. The advantage in expanding the simplified via is that it can often be sized to match the polygons to which the

The center to center spacing is 4 μm.

The size of an individual via is 2μm.


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via attaches. Having the via polygon edge and pad polygon edge in alignment can significantly reduce the subsection density in the region and thereby reduce the memory requirement of the model.

An example is shown below. The algorithm looks outward from an imaginary rectangle (bounding box) drawn around the perimeter of the array (green rectan-gle). The distance checked out from the perimeter is the Max Expansion Distance (shown in red arrows). It is equal to the Max Expansion Coefficient times the larg-est sized existing via in the array. If a vertex from a pad polygon is encountered within this window (red rectangle), the expansion stops and this sets the simplified polygon edge. If no vertices are found in a particular direction, the edge of the sim-plified via rolls back to the existing via array perimeter. Please note that all metal levels are examined when looking for vertices within the maximum expansion dis-tance.

The Max Expansion Distance is denoted by the red dashed box and is 7.0 times (default value) the largest via size (2.0 μm) = 14.0 μm.

The via array perimeter is indicated by the dashed green box. If no vertices are found in that direction, then the perimeter defines the edge of the simplified via in that direction.

The blue stars are vertices within the max expansion distance on this metal level. The yellow star indicates a vertex found on another metal level.

The dashed blue box above shows the final size of the simplified via. On the top, bottom and right hand side the via extends to the vertices and on the left side it conforms to the array bounding box (dashed green box) since no vertices were found within the maximum expansion distance in that direction.


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TIP

The default setting for Max Expansion Coefficient is 7.0. If you wish the simpli-fied via to be the bounding box around the array, set the Max Expansion Coeffi-cient to 0, which allows no expansion.

Merge Planar Polygons During Simplification

In order to be considered an array, a group of vias must connect to a single polygon on the top and bottom of the group. This control allows the user to merge the poly-gon pads or traces prior to simplifying the vias. This results in larger arrays being recognized leading to the least number of simplified vias, thereby producing the most efficient model. This option is enabled by default. The option is illustrated below using the example circuit.

NOTE: The polygons are only temporarily merged for via simplification and will not be merged in the resulting Sonnet project.

The trace is divided into two parts (black outlines show the two polygons).

If the Merge Planar Polygon option is not selected, then the array is treated as two via arrays (indicated by the dashed red boxes) and two simplified vias are created. If the option is on, however, the two parts of the trace are merged into one polygon and the whole array is simplified into one via.


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Number of New Via Metals Created

Via metal types using the Array loss model are created to model your simplified vias in Sonnet. This setting controls how many via metal types are created in your translated project in order to model your simplified array. The fill factor is used to determine how many metal types are created. For more information on the fill fac-tor and the Array loss model, please see “Array Loss Model” in the Sonnet User’s Guide.

There are three choices:

Minimum: Creates the least number of via metal types but may be less accurate as a wider range of fill factors will be grouped together.

Automatic: Creates the via metal types based on an algorithm that balances the trade off between accuracy and the number of via metal types produced. This is the default setting.

Maximum: Creates the highest number of via metal types providing the most ac-curate answer since a via metal type is created for each unique fill factor.

Simplified Via Array Loss

When an array is converted to a simplified via, a via metal type using the Array Loss model is created, if it does not yet exist. For example, you are translating an array which uses “ViaMetal1” for an array. During the translation a via metal type “ViaMetal1” is created that uses the Array Loss model. During translation, one source metal may be translated into two metal types if there is a significant differ-ence in individual via size in different arrays using the same metal. For more in-formation about via metal types and defining their loss, please see “Array Loss Model,” in the Sonnet User’s Guide.

The simplified via is modeled using the same meshing fill as the vias in the orig-inal via array. For a detailed discussion of meshing fill for via polygons, please see “Meshing Fill for Vias” in the Sonnet User’s Guide.


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Bar Via Group Simplification

Bar vias are vias whose length is significantly longer than their width. They are typically used in stacked multi-level conductors where vias carry horizontal cur-rents. An example is shown below, with one of the bar vias highlighted in black. For vias whose aspect ratio is smaller, such as 1:1, the Sonnet model assumes that there is little to no horizontal current in the via. The assumption is that current flows in the vertical or z-direction. For bar vias, whose aspect ratio is larger, the current flow in the horizontal direction is more significant. Bar via groups placed on metal traces also drive a very fine resolution in the meshing that can require an inordinate amount of processing resources.

The Identify Bar Vias feature identifies bar vias in the translated circuit based on length to width ratio entered by the user. These vias are assigned the Bar via mesh-ing fill, then during the analysis multiple adjacent bar vias are identified as a bar via group and merged into one wider via during the subsectioning by the analysis engine, em.

Since via arrays are simplified during translation, their appearance in the project editor is that of the simplified via polygon into which the via array was converted. However, in the case of bar vias, the actual via polygon input by the user is dis-played in the project editor, because no simplification has yet been done. If you wish to see the actual metal for the simplified bar vias that are used in the simula-


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tion, you should view the subsections for the circuit. For a detailed explanation of how bar vias are simplified and modeled by the analysis engine, please see “Sim-plifying Bar Vias in the Analysis Engine,” page 292 in the Sonnet User’s Guide.

NOTE: The Simplify Via Arrays feature must be on in order to use the Identify Bar Vias feature.

This feature can be invoked inside the Keysight ADS Interface, the Cadence Vir-tuoso Interface, and the NI AWR Microwave Office Interface. It may also be in-voked in Sonnet’s project editor when performing an import using the Gerber/ODB++ Translator, GDSII Translator or DXF Translator.

New Via Metals and Bar Via Loss

Metal used for bar vias should always use the Volume loss model since this model supports horizontal current. Any vias that use the Array loss model or the Surface loss model will not be identfied as bar vias during the simplification process.

Changes in meshing fill do not change the loss associated with a via polygon, only the way in which the via is subsectioned. Loss is based on the loss model used for the metal type. For more information about via metal types and the Volume loss model, please see “Volume Loss Model” in the Sonnet User’s Guide. Note that this description details the loss in the vertical direction. For the horizontal loss, bar vias are modeled in the same way as Thick metal. For more information on Thick metal modeling, see the “Thick Metal” chapter in the Sonnet User’s Guide. For a detailed discussion of meshing fill for via polygons, please see “Meshing Fill for Vias,” in the Sonnet User’s Guide.

Index

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Aair 10, 13array criteria 114array see via array simplification

Bbox

coupling 10definition 9

EEM structure editor

choosing Microwave Office 27enclosure 9example files

obtaining 74

Ffill type

setting globally in MWOffice 28setting locally in MWOffice 30

Gglobal settings 27

Llocal settings 27loss 9loss of simplified via array 120

Mmax distance to size ratio 116max expansion coefficient 117maximum size to size ratio 117merge planar polygons during

simplification 119microstrip 10, 13Microwave Office

unlocking 65working outside of 65

minimum vias in array 116

Nnumber of new via metals created 120,

122

Sshielding box 9simplify via arrays 113, 121

array criteria 114loss 120options 114–120

Vvia array simplification 113, 121

array criteria 114loss 120options 114–120

Index

Index

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14.52 Rev 1 - Sonnet Software Exporting Your EM Structure to Sonnet . . . . . . . . . 65 ... Chapter...

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