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Microwave Circuit Laboratory

Contents

Experiment 1 : Familiarization to ADS

1 Familiarization: ............................................................................................................................... 4

1.1 Features and Components ....................................................................................................... 4

1.2 Getting started ......................................................................................................................... 6

Experiment 2 : Wilkinson Power Divider

2 Wilkinson Power Divider ............................................................................................................... 9

2.1 Equal split (1:2) divider....................................................................................................... 10

2.2 Equal spilt (1:4) divider......................................................................................................... 11

2.3 Wilkinson power divider using Lumped elements ................................................................ 13

2.4 Wilkinson power divider using microstrip lines ................................................................... 15

Experiment 3 : Lowpass Filter Design

3 I. Maximally flat filter .................................................................................................................. 20

3.1 filter using Lumped elements ................................................................................................ 20

3.2 Maximally Flat filter using microstrip line ........................................................................... 22

3 II. Equal Ripple Filter ....................................................................................................................... 25


3.4 filter using microstrip lines ................................................................................................... 27

Experiment 4 : Bandpass Filter Design

4 I. Maximally flat bandpass filter: .................................................................................................... 34

4.1 Filter using Lumped elements ............................................................................................... 34

4.2 Filter using coupled line ........................................................................................................ 35

4 II. Equal ripple bandpass filter: ......................................................................................................... 38

4.3 Filter using lumped elements ................................................................................................ 38



EXPERIMENT 1

FAMILIARIZATION TO ADS


Contents

1 familiarization : ............................................................................................................................... 4

1.1 Features and Components ....................................................................................................... 4

1.1.1 Innovative and industry-leading simulation technologies ............................................... 4

1.1.2 Post processing with Data Display .................................................................................. 4

1.1.3 Design Optimization ........................................................................................................ 4

1.1.4 Easy layout in foundry’s specific process ........................................................................ 5

1.1.5 Catch errors early with ADS desktop DRC and LVS ...................................................... 5

1.1.6 Integrated Electro-Thermal Solver .................................................................................. 5

1.1.7 Innovative multi-technology capability ........................................................................... 5

1.1.8 Momentum 3D planar EM simulator ............................................................................... 5

1.1.9 Finite element method simulator ..................................................................................... 6

1.1.10 EMPro—ADS’s companion 3D EM simulation software ............................................... 6

1.2 Getting started ......................................................................................................................... 6

1.2.1 Step 1 - Creating Workspace: .......................................................................................... 6

1.2.2 Step 2: Creating Schematic Design .................................................................................. 6

1.2.3 Step 3: Circuit simulation ................................................................................................ 6

2.3.4 Observations: ................................................................................................................. 14


Aim : familiarization to Agilent Advanced Design System (ADS 2013.06)

1 Familiarization:

Advanced Design System is the world’s leading electronic design automation software for

RF, microwave, and high speed digital applications. It has a powerful and easy to use interface that

facilitates easy design, simulation and hardware realization of RF circuits and systems.

1.1 Features and Components

1.1.1 Innovative and industry-leading simulation technologies

• S-parameter linear frequency-domain simulator

• Harmonic balance nonlinear frequency domain simulator

• Circuit envelope hybrid time-/frequency domain nonlinear simulator

• Transient/convolution time-domain simulator

• Momentum 3D planar EM simulator

• Finite Element full 3D EM simulator

• X-parameter generator simulator

• Signal Integrity Channel simulator

• Agilent Ptolemy system simulator

1.1.2 Post processing with Data Display

A powerful Data Display capability allows learning about the design’s performance by post-

processing and analyzing the data without re-running simulation. Countless built-in functions

simplify the process.

1.1.3 Design Optimization

Once the initial design is done, ADS optimizers can further improve its nominal performance.

The ADS optimization cockpit provides an interactive environment with multiple optimization

variables, interactive tuning and progress controls. Using it, we can achieve optimal performance

while gaining design insight into the optimized variables versus the goals.


1.1.4 Easy layout in foundry’s specific process

ADS offers a full-featured tool for generating production ready RF layouts. With the largest

number of fully endorsed foundry design kits, ADS helps to layout your design in your foundry’s

specific process. The MMIC Toolbar and layout command line editor, available in all enhanced

foundry PDKs, ensures layout editing commands are easily accessible and provide a full suite of

layout verification tools.

1.1.5 Catch errors early with ADS desktop DRC and LVS

ADS Desktop design rule check (DRC) enables you to determine whether your physical

layout satisfies foundry design rules. Use ADS Desktop layout vs. schematic (LVS) to verify no

discrepancies exist between the layout and schematic, to identify missing components and easily find

and correct connections in your schematic or layout. ADS also support DRC/LVS with Calibre and

Assura directly from the ADS cockpit.

1.1.6 Integrated Electro-Thermal Solver

ADS provide a full 3-D thermal solver that is tightly integrated with the ADS layout

environment and circuit simulators. Simply add the Electro-Thermal controller to the ADS

schematic, start a circuit simulation and the integrated thermal solver will run in the background. No

more manual export of IC layouts to stand-alone thermal solvers; no more manual import of

temperature data into the circuit simulators.

1.1.7 Innovative multi-technology capability

ADS capabilities enable tradeoffs to be made interactively on the IC, laminate, packaging,

and printed circuit boards being designed or co-designed together. Circuits designed in multiple

technologies can be combined and simulated at both the circuit and full 3D EM level.

1.1.8 Momentum 3D planar EM simulator

Agilent’s Momentum is the leading 3D planar EM simulator used for passive circuit

modeling and analysis. It accepts multilayer design geometries and uses frequency-domain Method

of Moments (MoM) technology to accurately simulate complex EM effects (including coupling and

parasitic), improving performance and increasing confidence that manufactured products will meet

specifications.


1.1.9 Finite element method simulator

The Agilent FEM simulator element provides full-wave 3D EM simulation capabilities to

both ADS and its companion 3D EM simulation software, Electromagnetic Professional (EMPro).

FEM is a frequency-domain technique that can handle arbitrary shaped structures, employing both

direct and iterative solvers, and linear and quadratic basis functions, to solve a broad range of

problems. FEM is integrated into the ADS design flow to enable seamless co-simulation of arbitrary

components. This allows the effects of 3D components to be naturally accounted for without leaving

the circuit design flow. It is especially convenient for RF module designs where 3D interconnects

and packaging.

1.1.10 EMPro—ADS’s companion 3D EM simulation software

EMPro is a 3D modeling and simulation environment for analyzing the 3D EM effects of

high-speed and RF/microwave components.

1.2 Getting started To start with ADS, the steps below are followed

1.2.1 Step 1 - Creating Workspace:

i. Launch ADS2013 and from the main window select File->New-Workspace.

ii. Enter workspace name as desired. Select the libraries to be included in the workspace.

iii.Provide the library name under which user would like to organize the work.

iv.Select the preferred units to be used during the design.

1.2.2 Step 2: Creating Schematic Design

Usually circuit design will start from the schematic entry. To start the schematic design we

can begin from File->New->Schematic or by clicking on the Schematic icon on the main window

toolbar.

Create the circuit as desired.

1.2.3 Step 3: Circuit simulation

Simulation is done by pressing F7. Once done, data display showing the simulation results will be shown according to the selected simulation template.

Conclusion

The ADS software can be used to do RF circuit and system design and simulation.


EXPERIMENT 2

WILKINSON POWER DIVIDER


Contents

2 Wilkinson Power Divider ............................................................................................................... 9

2.1 Equal split (1:2) divider....................................................................................................... 10

2.1.1 Design Specifications..................................................................................................... 10

2.1.2 Circuit diagram .............................................................................................................. 10

2.1.3 Response of equal split 1:2 divider ................................................................................ 10

2.1.4 Observations .................................................................................................................. 11

2.2 Equal spilt (1:4) divider......................................................................................................... 11


2.2.2 Circuit diagram .............................................................................................................. 11

2.2.3 Response of equal split 1:4 divider ................................................................................ 12

2.2.4 Observations .................................................................................................................. 12

2.3 Wilkinson power divider using Lumped elements ................................................................ 13


2.3.2 Circuit diagram .............................................................................................................. 14

2.3.3 Response of lumped Wilkinson power divider .............................................................. 14

2.3.4 Observations: ................................................................................................................. 14

2.4 Wilkinson power divider using microstrip lines ................................................................... 15


2.4.2 Circuit diagram .............................................................................................................. 15

2.4.3 Layout ............................................................................................................................ 15

2.4.4 Response of Wilkinson divider using microstrip ........................................................... 16

2.4.5 Observations: ................................................................................................................. 16


Aim : Design Wilkinson power divider

Software : Advanced Design System 2013.06

Design Parameters :

Frequency : 1.5GHz

Source Resistance : 50Ω

Theory :

Wilkinson power divider is a 3 port power divider which provides isolation between the output ports while maintaining a matched condition on all ports. The Wilkinson design can also be used as a power combiner because it is made up of passive components and hence reciprocal. A tee junction can also be used as power divide but it will not provide matching at all ports. Resistive divider will provide matching at all ports but it is not lossless. If output ports are not matched then reflected power from the output ports is dissipated into resistor connected between output transmission lines. Wilkinson divider would appear to be lossless only output ports are matched.

2 Wilkinson Power Divider

Wilkinson power divider is implemented most often using quarter wave transformers as shown in figure below,

Above circuit can be analyzed by reducing it to two simpler circuits driven by symmetric and antisymmetric sources at the output ports. This is called “even-odd” mode analysis technique.Using even-odd mode analysis we get S matrix as follows,

√2 0 1 11 0 01 0 0


2.1 Equal split (1:2) divider

2.1.1 Design Specifications

Operating Frequency : 1.5GHz


Power Output : -3 dB

2.1.2 Circuit diagram

2.1.3 Response of equal split 1:2 divider


2.1.4 Observations

1. Minimum reflection at port 1 -64dB from S(1,1) at 1.5GHz .

2. Equal power at output ports -3dB (i.e. Half of input power) from S (2, 1), S (3, 1) at 1.5GHz.

3. Very high isolation between output ports -72dB at 1.5GHz from S (2, 3)

2.2 Equal spilt (1:4) divider







2.2.3 Response of equal split 1:4 divider

2.2.4 Observations

1. From S(1,1)at 1.5 GHz minimum power reflected back to port 1.

2.From S(2,1),S(3,1),S(4,1),S(5,1) power is equally divided (-6dB) into all four ports.

3. From S(2,3) high isolation between output port 2 and 3 (-78dB).Similarly for all output ports at 1.5GHz


2.3 Wilkinson power divider using Lumped elements

Wilkinson divider generally implemented using quarter wave transmission line sections at the design frequency, which can have unrealistic dimensions at frequencies in the RF and low microwave bands, where the wavelength is large.

For example, a λ/4 microstrip line with characteristic impedance Zo = 70.7Ω on FR-4 substrate (dielectric constant εr= 4.3, thickness h= 1.0 mm) is approximately 43 mm long at 1 GHz.

In some cases, it would be preferable to use lumped-element equivalent networks replacing the λ/4 transmission lines . It is possible to employ surface mount devices (SMD), as well as monolithic microwave integrated circuit (MMIC) lumped elements , which allow saving circuit area.

By using lumped element equivalent of transmission

where

12

2

The “Pi” LC network is perfectly equivalent to the line section only at the center frequency fo,

but the approximation is still valid for modest bandwidths.







2.3.3 Response of lumped Wilkinson power divider

2.3.4 Observations:

1.Minimum power (-65dB) is reflected and from S(1,1) at 1.5 GHz respectively.

2. Equal power at output ports (-3.010dB) i.e. half of input power from S (2,1), S(3,1) at 1.5 GHz.

3. Maximum isolation (-72dB) at 1.5GHz from S(2,3)

S-PARAMETERS

S_Param

Term

Term

Term

C C

C

R

L

L

SP1

Term3

Term2

Term1

C3 C2

C1

R1

L2

L1

Step=0.01 GHz

Stop=3 GHz

Start=0 GHz

Z=50 Ohm

Num=3

Z=50 Ohm

Num=2

Z=50 Ohm

Num=1

C=3 pF C=1.5 pF

C=1.5 pF

R=100 Ohm

R=

L=7.5068 nH

R=

L=7.5068 nH


2.4 Wilkinson power divider using microstrip lines






2.4.3 Layout


2.4.4 Response of Wilkinson divider using microstrip

2.4.5 Observations:

1. From S (1, 1) and S (2,3) minimum power (-47dB) is reflected and maximum isolation(-40dB) at 1.5 GHz respectively.

2. From S (2, 1), S (3, 1) equal power (-3.414dB) is divided between two ports at 1.5 GHz.


EXPERIMENT 3

LOW PASS FILTER DESIGN


Contents

3 I. Maximally flat filter .................................................................................................................. 20


3.1.1 Scaled element values .................................................................................................... 20

3.1.2 Circuit diagram .............................................................................................................. 21

3.1.3 Filter response using lumped elements .......................................................................... 21

3.1.4 Observation .................................................................................................................... 21

3.2 Maximally Flat filter using microstrip line ........................................................................... 22

3.2.1 Microstrip Line parameters ............................................................................................ 22

3.2.2 Circuit Diagram ............................................................................................................. 22

3.2.3 Maximally flat response using microstrip line.............................................................. 23

3.2.4 Maximally flat filter after tuning ................................................................................... 23

3.2.5 Maximally flat response after tuning ............................................................................. 24

3.2.6 Observations .................................................................................................................. 24

3.2.7 Layout ............................................................................................................................ 24

3 II. Equal Ripple Filter ....................................................................................................................... 25



3.3.2 Circuit Diagram ............................................................................................................. 26

3.3.3 Equal Ripple Response with lumped elements .............................................................. 26

3.3.4 Observation .................................................................................................................... 26

3.4 filter using microstrip lines ................................................................................................... 27


3.4.2 Circuit Diagram ............................................................................................................. 27

3.4.3 Equal ripple microstrip Filter response .......................................................................... 28

3.4.4 Equal Ripple filter with tuned values............................................................................. 28

3.4.5 Equal ripple response after tuning ................................................................................. 29

3.4.6 Observations .................................................................................................................. 29

3.4.7 Layout ............................................................................................................................ 29


Aim : Design a 3rd order Low Pass Filter using Insertion Loss method using maximally flat and butterworth distributions.


Theory :

Insertion loss method :

A perfect filter would have zero insertion loss in the passband, infinite attenuation in the stopband, and a linear phase response (to avoid signal distortion) in the passband. such filters do not exist in practice.So we use distributions like maximally flat or equal ripple so as to charcterise practical filter response.

In the insertion loss method a filter response is defined by its Insertion loss, or power loss ratio

!!"! # ! 11 |Γ&'(|)

The Insertion loss (IL) in dB is

* 10+

1.Maximally flat :

This characteristic is also called thebinomialorButterworthresponse, and is optimum in the sense that it provides the flattest possible passband response for a given filter complexity, or order. For a low-pass filter, it is specified by

1 + -) . ''/0)1

2. Equal Ripple :

If a Chebyshev polynomial is used to specify the insertion loss of an Nthorder low-pass filter as

1 + -)21) . ''/0

then a sharper cutoff will result, although the passband response will have ripples of amplitude 1 + -) since 21(x) oscillates between ±1 for |x|.


3 I. Maximally flat filter

Design Specifications

Cutoff Frequency : 1.5 GHz


Insertion loss (at 2.5 GHz) > 10dB

Fillter Order calculations :

334 1 = ).67.6 1 0.6667

From Attenuation Verses normalized frequency graph from maximally flat filters (Microwave engineering Pozar Fig no. 8.26) for obtaining insertion loss > 10 dB order of filter is 3.

3.1 filter using Lumped elements

3.1.1 Scaled element values

Element values for 3rd order Butterworth low prototype are given by

N=3 For g0=1 and '/ = 1

g1=1.0000 g2=2.0000 g3=1.0000 g4=1.0000

For source resistance = 50Ω , '/ = 1.5GHz

By using Impedance and Frequency Transformations as

:; <34

:; =<34

L1=5.305 nH C1=4.244 pF L2=5.305 nH



3.1.3 Filter response using lumped elements

3.1.4 Observation

1. 3dB cutoff frequency fc=1.5GHz

2. Insertion loss at 2.5 GHz is 13.508


3.2 Maximally Flat filter using microstrip line

Converting to microstrip by using Richards transformations and kuroda’s Identities

And using Line calc tool from ADS to calculate length and width of microstrip transmission lines.

3.2.1 Microstrip Line parameters

Line Impedence(Ω) Width(mm) Length(mm) Type

TL3,TL4 100 0.606875 14.132600 > 8⁄ line TL7 25 7.976470 12.672800 > 8⁄ open stub TL5,TL6 100 0.606875 14.132600 > 8⁄ open stub TL1,TL2 50 2.860030 26.699100 > 4⁄ line

3.2.2 Circuit Diagram


3.2.3 Maximally flat response using microstrip line

3.2.4 Maximally flat filter after tuning


3.2.5 Maximally flat response after tuning

3.2.6 Observations

1. Using Microstrip lines 3dB cutoff frequency fc=1.436 GHz. So tuning is required

2. After tuning 3dB cutoff frequency fc=1.5GHz

3. Insertion loss after tuning is 35.447 dB

3.2.7 Layout


3 II. Equal Ripple Filter

Design Specifications

Cutoff Frequency : 1.5 GHz


Ripple : 3 dB equal ripple

Insertion loss (at 2.5 GHz) > 20dB

Fillter Order calculations :

334 1 = ).67.6 1 0.6667

From Attenuation Verses normalized frequency graph from maximally flat filters (Microwave engineering Pozar Fig no. 8.27b) for obtaining insertion loss > 20 dB order of filter is 3.

3.3 filter using Lumped elements


Element values for 3rd order low pass filter equal ripple prototype are given by

For N=3 g0=1 '/ = 1

g1=3.3487 g2=0.7117 g3= 3.3487 g4=1.0000

For source resistance = 50Ω, '/ = 1.5GHz

By using Impedance and Frequency Transformations as

:; <34 :; =<34

L1=17.765 nH C1=1.51 pF L2=17.765 nH



3.3.3 Equal Ripple Response with lumped elements

3.3.4 Observation

1. 3dB cutoff frequency fc=1.5GHz

2. 3 dB equal ripple at 750MHz and 1.5 GHz

2. Insertion loss at 2.5 GHz is 22.619 dB


3.4 filter using microstrip lines

Using Richard’s transformations and converting lumped elements to transmission line and then using kuroda’s Identity 2 we get Equal ripple filter using microstrip lines. By using line calc in ADS


Line Impedence(Ω) Width(mm) Length(mm)

TL5,TL6 217.5 0.005741 15.269600 > 8⁄ line TL7 70.3 1.490720 13.735300 > 8⁄ open stub TL3,TL4 64.9 1.761860 13.643300 > 8⁄ open stub TL1,TL2 50 2.860030 26.699100 > 4⁄ line



3.4.3 Equal ripple microstrip Filter response

3.4.4 Equal Ripple filter with tuned values


3.4.5 Equal ripple response after tuning

3.4.6 Observations

1. Using microstrip lines: i. 3dB cutoff frequency fc= 1.246 GHz

ii. Ripple at 750MHZ is -4.063 dB and at 1.5GHz is 7.76 db.

iii. Insertion loss at 2.5GHz is 47.675

Therefore tuning is necessary.

2. After tuning: i. Cutoff frequency = 1.5GHz

ii. 3dB equal ripple at 750MHz and 1.5GHz.

iii. Insertion loss at 2.5GHz is 41.775dB

3.4.7 Layout


EXPERIMENT 4

BAND PASS FILTER DESIGN


Contents

4 I. Maximally flat bandpass filter: ................................................................................................. 34

4.1 Filter using Lumped elements ............................................................................................... 34


4.1.2 Circuit Diagram ............................................................................................................. 34


4.1.4 Observations .................................................................................................................. 35


4.2.1 Coupled line parameter calculations .............................................................................. 35

4.2.2 Circuit diagram .............................................................................................................. 36

4.2.3 Filter Response using coupled lines ............................................................................... 36

4.2.4 Observations .................................................................................................................. 37

4.2.5 Layout ............................................................................................................................ 37

4 II. Equal ripple bandpass filter: ......................................................................................................... 38

4.3 Filter using lumped elements ................................................................................................ 38


4.3.2 Circuit Diagram ............................................................................................................. 38


4.3.4 Observations .................................................................................................................. 39


4.4.1 Coupled line parameter calculations .............................................................................. 39

4.4.2 Circuit Diagram ............................................................................................................. 40

4.4.3 Filter response using coupled lines ................................................................................ 40

4.4.4 Observations .................................................................................................................. 41

4.4.5 Layout ............................................................................................................................ 41


Aim : Design a 3rd order Band Pass Filter using Insertion Loss method using maximally flat and butterworth distributions.


Theory :

Low-pass prototype filter designs can also be transformed to have the bandpass or bandstop

responses . If '7and ') denote the edges of the passband, then a bandpass response can be obtained using the following frequency substitution:

B ← D∆. BBF BFB 0

Where ∆ BGHBDBF where ∆ is fractional bandwidth of the passband.

The center frequency 'could be chosen as the geometric mean.

BF IBDBG

a series inductor Lk is transformed to a series LC circuit and a shunt capacitor Ck is transformed to a shunt LC circuit as shown in figure below,


Bandpass Filter Design using Coupled lines

The parallel coupled transmission lines can be used to construct many types of filters. Fabrication of multi-section bandpass or bandstop coupled line filters is particularly easy in microstrip or stripline form for bandwidths less than about 20%. Wider bandwidth filters generally require very tightly coupled lines, which are difficult to fabricate. In this method the half wave resonators are positioned so that adjacent resonators are parallel to each other along half of their length.

A two-port network can be formed from a coupled line section by terminating two of the four ports with either open or short circuits, or by connecting two ends. For couple line bandpass filters port 2 and port 4 are kept open, as open circuits are easier to fabricate in microstrip than short circuits.

Single coupled line section can be approximately modeled by the equivalent circuit shown below,

By calculating the image impedance and propagation constant of the equivalent circuit and showing that they are approximately equal to those of the coupled line section for=π/2, which will correspond to the center frequency of the bandpass response. Even- and odd-mode line impedances for above equivalent circuit is given by

JFK JF ∗ MD + NJF + NJFGO JFP JF ∗ MD NJF + NJFGO

Narrowband bandpass filters can be made with cascaded coupled line sections. For cascaded sections design equations are given by

NDJF Q R∆GSD NTJF R∆GISTHDST

NTUDJF Q R∆GSTUDST


4 I. Maximally flat bandpass filter:

Design Specifications :

Center Frequency : 1.5GHz

Bandwidth : 0.3 GHz

∆ = 0.2


4.1 Filter using Lumped elements


Element values for 3rd order Butterworth low prototype are given by

N=3 g1=1.0000 g2=2.0000 g3=1.0000

By using lowpass to bandpass Transformations

L1=26.256 nH C1=0.4244 pF

L2=0.54112632 nH C2=21.221 pF

L3=26.256 nH C3=0.4244 pF




4.1.4 Observations

1. Center Frequency fc=1.5GHz

2. Insertion Loss at Center frequency 0 dB

3.-3dB cutoff frequency 1.350 GHz and 1.650GHz

4. Bandwidth 300 MHz

4.2 Filter using coupled line

4.2.1 Coupled line parameter calculations

Using design equations for cascaded sections of coupled given in theory above calculate even and odd mode impedances. Then using Line calc tool from ADS to calculate length ,width and spacing between coupled lines.

n ST NTJF JFK(Ω) JFP (Ω) Width w

(mm) Length l

(mm) Spacing s

(mm) 1 1 0.5605 93.7329 37.6830 1.4659722 26.178952 0.216565

2 2 0.2221 63.5714 41.3614 2.51538 26.635616 0.82852 3 1 0.2221 63.5714 41.3614 2.51538 26.635616 0.82852 4 1 0.5605 93.7329 37.6830 1.4659722 26.178952 0.216565



4.2.3 Filter Response using coupled lines


4.2.4 Observations

1. Center Frequency fc =1.5GHz

2. Insertion Loss at Center frequency -2.310 dB

3. -3dB cutoff frequency 1.350 GHz and 1.650GHz

4. Bandwidth 300MHz

4.2.5 Layout


4 II. Equal ripple bandpass filter:

Design Specifications :

Center Frequency : 1.5GHz

Bandwidth : 0.3 GHz

∆ = 0.2


4.3 Filter using lumped elements


Element values for 3rd order 3dB equal ripple low prototype are given by

N=3 g1=3.3487 g2=0.7117 g3=3.3487

By using lowpass to bandpass Transformations

L1=88.827 nH C1=0.12674 pF

L2=1.491 nH C2=7.5514 pF

L3=88.827 nH C3=0.12674 pF




4.3.4 Observations


2. Insertion Loss at Center frequency 0 dB


4. -3dB equal ripple at 1.425GHz and 1.575GHz

5. Bandwidth 300MHz

4.4 Filter using coupled line

4.4.1 Coupled line parameter calculations

Using design equations for cascaded sections of coupled given in theory above calculate even and odd mode impedances. Then using Line calc tool from ADS to calculate length ,width and spacing between coupled lines.

n ST NTJF JFK(Ω) JFP (Ω) Width w

(mm) Length l

(mm) Spacing s

(mm)

1 3.3487 0.3063 70.0060 39.3760 2.48669 26.668154 0.50729888

2 0.7117 0.2035 62.2456 41.8956 2.62484 26.32424 0.8598878 3 0.7117 0.2035 62.2456 41.8956 2.62484 26.32424 0.8598878 4 1 0.3063 70.0060 39.3760 2.48669 26.668154 0.50729888



4.4.3 Filter response using coupled lines


4.4.4 Observations


2. Insertion Loss at Center frequency -3.8 dB


4. Ripple at 1.425GHz is -5.648dB and at 1.575GHz is -5.962dB

5. Bandwidth 300MHz

4.4.5 Layout

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