CoventorWare

Mini Project Report Design of Modified CPW switch using Coventorware

Design of Modified CPW switch using Coventorware

MINI PROJECT REPORT

Submitted as part of the coursework

of

Master of Technology

In

COMMUNICATION SYSTEMS

Of

NATIONAL INSTITUTE OF TECHNOLOGY, TIRUCHIRAPPALLI

By

SUJAY PUJARI (208109013)

Department Of Electronics and Communication Engineering

National Institute of Technology

Tiruchirappalli - 620 015

2010

Dept. of ECE, NIT Trichy 1


NATIONAL INSTITUTE OF TECHNOLOGY

TIRUCHIRAPPALLI, TAMIL NADU – 620 015

DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING

CERTIFICATE

Certified that the mini project work titled “Cesign of

modified CPW switch using Coventorware is a

bonafide report of the mini project done by Srijith K

(208109015) of second semester M.Tech in

Communication Systems of the National Institute of

Technology, Tiruchirappalli during the academic year

2010.

Dr.S.RaghavanProject Guide

Place : Tiruchirappalli



Date :

ACKNOWLEDGEMENT

First of all I would like to thank God almighty for his divine grace and blessings

throughout this project.

I wish to thank my Project Guide, Dr.S.Raghavan for his guidance he showed us right

through every stage of the project, from the initial conception to final design and

simulation.

I would also like to extend my sincere thanks to my classmates, friends and family for

their whole-hearted support and encouragement.



ABSTRACT

The project aims to design and compare the pull-in voltages of different

flexures. Flexures are structures used to reduce the spring constant of beams.

Different flexures were designed for a fixed-fixed beam using CoventorWare. These

flexures were analyzed using the Analyzer tools of CoventorWare namely

MemElectro, MemMech and CoSolve EM. Pull in voltage analysis was also

performed and the pull in voltage of different flexure designs were compared.

The report will reflect on the principles and procedures of CoventorWare,

design details of flexures and the results and conclusions.



CONTENTS

1. INTRODUCTION.........................................................................................01

2. COVENTORWARE......................................................................................02

2.1 INTRODUCTION..................................................................................02

2.2 MPD EDITOR........................................................................................04

2.3 PROCESS EDITOR...............................................................................05

2.4 LAYOUT EDITOR................................................................................07

2.5 MEM ELECTRO....................................................................................10

2.6 MEM MECH..........................................................................................11

2.7 COSOLVE EM.......................................................................................12

3. DESIGN OF CPW SWITCH USING TWO CANTILIVERS......................13

4. RESULTS & CONCLUSIONS.....................................................................14

4.1 RESULTS..............................................................................................14

4.2 CONCLUSIONS....................................................................................15

5. REFERENCES..............................................................................................16



1. INTRODUCTION

Switches play a main role in MEMS. These are the basic structures which

are used to implement any RF modules in RF MEMS. There are two type of switches

1. Series switch,

2. Shunt switch

For CPW switch usually fixed fixed beam shunt switch is preferred. In this

project we have designed a CPW switch with two cantilever switches using

COVENTORWARE software.



2. COVENTOR

2.1 INTRODUCTION

CoventorWare is an integrated suite of software tools for designing and simulating

MicroElectroMechanical Systems(MEMS).

CoventorWare supports two distinct design flows illustrated in fig 2.1. They are

i) ARCHITECT.

ii) DESIGNER and ANALYZER.

The ARCHITECT module provides a unique system-level approach to MEMS design.

The user assembles a schematic of the MEMS device by selecting and connecting

components from a library of parameterized, MEMS-specific behavioral models.

Upon completing a schematic, the user can simulate various aspects of its physical

behavior. The advantages of this system-level modeling approach include full

parameterization of the design and very fast simulations

Fig 2.1 : Design flow in Coventor



The DESIGNER and ANALYZER modules support a physical design flow. The user

starts in DESIGNER by creating a 2-D layout in the Layout Editor. The Solid

Modeler uses the layout, in conjunction with the layer stack information provided in

the Process Editor, to automatically build a 3-D solid model. The user then works in a

3-D view in the Preprocessor to prepare the 3-D model for automatic mesh

generation. After a mesh has been generated, the user can select from a

comprehensive suite of field solvers that simulate the physical behavior of MEMS.

Both design flows require information about the fabrication process as a starting

point, and this information is provided via a Process Editor and the Material

Properties Database. The INTEGRATOR module provides a bridge from detailed 3-D

physical simulations in ANALYZER to the ARCHITECT system-level modeling

environment

Fig 2.2 : Function Manager window



The Function Manager window shown in Fig 2.2 is the first to appear. All

CoventorWare functionality is accessed from the Function Manager. It consists of the

following:

Material Properties Database: The first step in creating a design is to enter

the material properties associated with your fabrication process in the Material

Properties Database (MPD). Only the materials that are in the MPD are

accessible in the Process Editor and available for simulations.

Process Editor: The second step in creating a design is to enter a description

of the sequence of steps involved in the fabrication process in the Process

Editor.

Analyzer 3-D Field Solvers: Analyzer provides a comprehensive suite of

3-D solver. With these solvers, you can perform analyses.

2.2 MATERIALS EDITOR

Material Properties Database (MPD) file

Contains commonly used materials for MEMS processing

Includes mechanical, electrical, thermal, fluidic, and other generic material

property values.



2.3 PROCESS EDITOR

Coventor uses Surface micromachining

Surface micromachining – addition and removal of sequence of thin film

layers to/from the wafer surface

Sacrificial & structural layers

Depends on the ability to release/dissolve the sacrificial layers while

preserving the integrity of structural layers

build or edit a simulated process flow that models the fabrication process to be

used

The 2-D mask definitions in the layout are combined with the depth

information in the process to create a model.



2.4 LAYOUT EDITOR

Purpose: Generate 2-D masks

Tasks performed by icons, point-and-click mouse functionality, the menu bar

and drop-down menus, and Terminal Window commands.

Graphic tool

User interface dialogs

Drawing area

Terminal window

Icons

Menu selections



3D MODEL GENERATION:



2.5 MEM ELECTRO

With the CoventorWare solvers, the user can run various

simulations on a model created and meshed in the Preprocessor or

on a model imported and converted to the CoventorWare file

format. CoventorWare’s electrostatic solver, MemElectro, can

compute a matrix of capacitance and conductance values or can

compute forces on conductors and dielectrics for MEMS designs.

MemElectro applies selected solver settings and boundary

conditions and computes the appropriate results. The output may be

viewed in a tabular form or rendered in three dimensions over the

structure’s domain in the Visualizer.

The flow chart in Fig 2.11 provides an overview of the MemElectro

functions.



Fig 2.11 : Functions of MemElectro

2.6 MEM MECH

MemMech is CoventorWare’s mechanical solver, which computes

displacement and stress results. The user applies the boundary

conditions set in solver dialog, and the solver generates output that

may be viewed in a tabular form or rendered in three dimensions

over the structure’s domain in the Visualizer. The flow chart in Fig

2.12 provides an overview of the MemMech functions:



Fig 2.12 : Functions of MemMech

2.7 COSOLVE EM

CoSolveEM provides the capability of coupled quasi-steady

electromechanical analysis. A typical application is the analysis of

the electrostatic actuation of restrained mechanical structures.

MemElectro provides the electrostatic analysis, and MemMech

provides the mechanical analysis. CoSolve uses an iterative



procedure to maintain consistency between the two solutions, that

is, the mechanical deformation is correct for the applied

electrostatic forcing. The most common application is determination

of the so-called "pull-in" voltage, but other applications are useful as

well, including investigation of contact and lift-off behavior and

electrostatic spring softening. Typically, simulations are conducted

in the form of a traversal of a trajectory of actuation voltages (or

charges), but a single excitation condition can also be investigated.

The setup of a CoSolve simulation requires that MemMech be set up

for the mechanical analysis parameters and boundary conditions

and that MemElectro be set up for the electrostatic analysis

parameters and boundary conditions.The user should set

parameters for these solvers before setting CoSolve parameters.

3. DESIGN OF CPW SWITCH WITH TWO CANTILEVERS

Layout:



3D model:

4. RESULTS & CONCLUSION



MemMech analysis:

Pullin Voltage Analysis: Pull in voltage=13.2v

CONCLUSION:



The original CPW switch was modified with two cantilevers and its

pullin voltage was obtained.



5. REFERENCES

1. MEMS Design and Analysis Tutorials, Vol. 1, Physical and System Level

Design, CoventorWareTM 2008; www.coventor.com

2. CoventorWare DesignerTM Version 2008; Reference: MEMS and

Microsystems Physical Design; www.coventor.com


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