MWO – APPLICATION IN FILTER DESIGN Soh Ping Jack Sabarina Ismail

MWO – APPLICATION IN FILTER DESIGN

Soh Ping Jack

Sabarina Ismail

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1.0 FILTER DESIGN PROCESS

Filter Specification

Low-pass Prototype

Design

Scaling & Conversion

Filter Implementation

Optimization & Tuning

Done using MWO

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Filter Specification

Low-pass Prototype

Design

Scaling & Scaling & ConversionConversion

Filter Filter ImplementationImplementation

Optimization Optimization & Tuning& Tuning

Done using Done using MWOMWO

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1.2 GENERAL STEPS IN FILTER DESIGN

A. Know your filter specifications

1. Max Flat/Equal Ripple,

2. LPF/HPF/BPF/BSF

3. Desired freq of operation

4. Passband & stopband range

5. Max allowed attenuation (for Equal Ripple)

B. Design your LPF Prototype

1. Min Insertion Loss level, No of Filter Order/Elements

2. Determine whether shunt cap model or series inductance model to

use

3. Determine elements’ values from Prototype Table

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Filter Filter SpecificationSpecification

Low-pass Low-pass Prototype Prototype

DesignDesign

Scaling & Conversion

Filter Filter ImplementationImplementation

Optimization Optimization & Tuning& Tuning

Done using Done using MWOMWO

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C. Scaling & Conversion

1. Draw LPF filter prototype

2. Determine if there are any conversion to

HPF/BPF/BSF required

3. If yes, convert the LPF to the desired HPF/BPF/BSF

filter prototype. If no, move on to step 4.

4. Use equations to de-normalize cap & inductance

values

5. Re-draw de-normalized filter prototype

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Filter Filter SpecificationSpecification

Low-pass Low-pass Prototype Prototype

DesignDesign

Scaling & Scaling & ConversionConversion

Filter Implementation

Optimization & Tuning

Done using MWO

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D. Filter Implementation & Optimization

1. Draw de-normalized LPF filter prototype

with elements’ values

2. Implement filter prototype on software

3. Optimize & tune filter to get best response

To do this you have to be familiar with MWO

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2.0 KNOW YOUR SOFTWARE - BASIC

2.1 Working in the Circuit

Schematic Environment

2.2 Selecting & placing elements

2.3 Setting project frequency

range

2.4 Changing elements’ values

2.5 Adding result Graphs & Charts

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2.1 Working in the Circuit

Schematic Environment

2.22.2 Selecting & placing elements Selecting & placing elements

2.32.3 Setting project frequency Setting project frequency

rangerange

2.42.4 Changing elements’ valuesChanging elements’ values

2.52.5 Adding result Graphs & ChartsAdding result Graphs & Charts

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2.1 Working in the Circuit Schematic Environment

To add a new Schematic, right-click on “Circuit Schematic”

icon and select “New Schematic”

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2.1 Working in the Circuit Schematic EnvironmentA pop-up window like this will

appear after clicking “New

Schematic”, click on “OK”

button after entering the desired

name

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2.1 Working in the Circuit Schematic Environment

A blank schematic like this will

appear. It is used for the

placement of

components/elements

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2.12.1 Working in the Circuit Working in the Circuit

Schematic EnvironmentSchematic Environment

2.2 Selecting & placing elements


rangerange



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2.2 Selecting and Placing Elements

To select a specific element, ensure that the “Elem” tab is selected. Elements are sorted

into categories as shown in the box above

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For example, to select a capacitor, select “Capacitor” categories on the top box. A

specific capacitor then can be selected from the box at the

bottom

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To insert the desired element into the schematic, click on the specific element in the bottom box and drag till an

outline of the element appear as shown. Click

again to place the element

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2.22.2 Selecting & placing elementsSelecting & placing elements

2.3 Setting project frequency

range



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2.3 Setting project frequency range

To edit simulation freq sweep/range, double-click on the “Project Options” icon

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2.3 Setting project frequency range

Define desired “Start Freq”, “Stop Freq” & “Freq Step”. It should not be too refined in

an initial simulation

List of the simulated freq points will be listed down when “Apply” button is

clicked

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rangerange



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To add edit an element’s value, double-click on the

element’s default value and enter a desired value

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2.4 Changing elements’ values – Add Port

To add a port on a specific section of a line, click on the

“Ports” icon and select “PORT”

Place the port on the schematic section by clicking once on the desired location

Adding a port can be also done by clicking on the

“Ports” icon from the top toolbar

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2.4 Changing elements’ values – Add Ground

To add a ground, click on the “Ground” icon and select it. Click once and an outline of

it will appear

Place the ground on the schematic section by clicking once on the desired location

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rangerange


2.5 Adding result Graphs & Charts

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2.5 Adding result Graphs & Charts – Add Graph

To add a result graph, right-click on the “Graph” icon on the left window and select “Add Graph”. A pop-up

window will appear

Ensure that the “Proj” tab is selected before adding in any graphs

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2.5 Adding result Graphs & Charts – Graph Types

When a pop-up window like this will appear, select the appropriate type of

graph

Rename the graph as preferred

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2.5 Adding result Graphs & Charts – Add Meas

After inserting the appropriate graph type, it still does not know what type of parameters that is to be plotted on it.

To define this, right click on the “Graph’s Name” and click on “Add

Measurement”

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2.5 Adding result Graphs & Charts – Select Meas

A pop-up window like this will appear, select the correct EM Structure’s result

to be plotted by selecting the correct Data Source Name

Check on the correct parameter. In this case, it is S21. Ensure that the “dB”

checkbox is checked

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2.5 Adding result Graphs & Charts – Simulate

To start simulation, click on the Analyze button on the tool bar at the

top

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2.5 Adding result Graphs & Charts – Results

Filter Design CriteriaA good S11 will have a response at the desired design freq with < -10dB value

in pass bandA good S21 will have almost 0dB

response in pass band, & infinite response in stop band

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3.0 D.I.Y No. 1

Simulate the following design in MWO. Save the file.

CAPID=C1C=0.9833 pF

CAPID=C3C=3.182 pF

INDID=L2L=6.436 nH

INDID=L4L=6.436 nH

CAPID=C5C=0.9833 pF

PORTP=1Z=50 Ohm

PORTP=2Z=50 Ohm

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3.1 KNOW YOUR SOFTWARE - INTERMEDIATE

3.1.1 Selecting & Setting Variables

3.1.2 Analyzing & Tuning

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Re-open the file that was saved earlier in DIY No 1.

CAPID=C1C=0.9833 pF

CAPID=C3C=3.182 pF

INDID=L2L=6.436 nH

INDID=L4L=6.436 nH

CAPID=C5C=0.9833 pF

PORTP=1Z=50 Ohm

PORTP=2Z=50 Ohm

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To start manual tuning of certain parameters in a schematic, the “Tune

Tool” in the schematic should be selected

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Using the tune tool, select the desired parameter in the schematic to be

tuned. When selected its value will turn blue

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Invoke the variable tuning toolbar by clicking on the “Tune” button at the

top tool bar

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A variable tuning toolbar like this will appear before you. The nominal, max and min tunable values/range can be

set here by users

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Click on “Analyze” button and click on the Graph so that the results may be shown. Ensure that the variable tuner

tool bar is also easily accessible.

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Move the variable tuner up and down (to change the L value) and observe the changes in the S11 and S21 values

in the freq range

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4.0 KNOW YOUR SOFTWARE - ADV

4.1 Selecting & Setting Variables

4.2 Adding & Setting Optimization

Goals

4.3 Running an Optimization

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4.24.2 Adding & Setting Optimization Adding & Setting Optimization

GoalsGoals

4.34.3 Running an OptimizationRunning an Optimization

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To edit the property of variables for optimization purposes, click on “Simulate” button at the top of

window. Select “Optimize” option, OR press “F7” button

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A window like this will appear. Click on the “Variables” tab at the bottom of

the window to enable variable selection

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A window like this will appear. Select all the elements in the schematic and enable both options for tuning and

optimization

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A pop-up window like this will appear. Select the element’s Value (only) for

optimization and tuning. In this case, inductance “L” is selected for

tuning & optimization

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Another way of having a clearer view when selecting a certain (not all)

elements to be tuned and optimized is to double-click on the element in the

schematic

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4.14.1 Selecting & Setting VariablesSelecting & Setting Variables

4.2 Adding & Setting Optimization

Goals

4.34.3 Running an OptimizationRunning an Optimization

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4.2 Adding & Setting Optimization Goals

To set optimization goals, right-click on the “Optimization Goals” icon on the

right and select “Add Opt Goal”

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To add a goal so that S11 less than -10 dB in pass band, ensure that the S11 measurement is selected

here

Since this is an LPF with pass band < 2GHz, the range of the goal should start from MIN and

stops at 2GHz

Click on “OK” button when done setting an

optimization goal

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An optimization goal will appear under the “Optimizer Goals” icon when setting is

done

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An optimization goal line will also appear in the graph

where the optimized measurement is plotted.

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• Continue to add on another two more

optimization goals, which are both for S21;

1. S21 is at least -3 dB in pass band

2. S21 is less than – 10 db in stop band

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Goal 1: S21 is at least -3 dB in pass band

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Goal 2: S21 is less than – 10 db in stop band

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Optimization goal lines will also appear in the graph where the optimized measurement is

plotted. Colors of the lines are according to the measurement types, different measurement has

different goal line colors

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4.14.1 Selecting & Setting VariablesSelecting & Setting Variables

4.24.2 Adding & Setting Optimization Adding & Setting Optimization

GoalsGoals


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To start running an optimization, click on

“Simulate” and “Optimize” option at the top of the

window. User can also press “F7” button

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Once a window as shown appears, click on the “Start” button. Please also ensure

that the “Maximum Iterations” option is set to

“5000”

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When the “Show all iterations” check box is selected, no of iterations

during optimization run will be shown here.

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Final S11 and S21 response of the optimized filter is shown in the graph.

The optimizer tries to fit curves towards the goal targets, but might

not achieve it 100% due to the property of the filter itself

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Optimized circuit element’s value is shown in this figure

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5.0 CONCLUSION

• What you have learnt today??

• Revised on design theories learnt in class

• Applied a theory based design using a simulation

software

• Learnt how to use a software which is capable of

simulating various microwave components

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5.0 REFERENCES

• Pozar, D.M. (2005) Microwave Engineering 3rd Ed.

John Wiley & Sons, N.J, USA

• Pozar, D.M. (2001) Microwave and RF Design for

Wireless Systems, John Wiley & Sons, N.J, USA

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6.0 REVISION HISTORY

Version Date Comments Author

R01.00 22-08-2006 Initial Draft P.J Soh

R01.01 29-08-2006 Added Manual Tuning Proc (Section 3.1)

P.J Soh

Documents

MWO – APPLICATION IN FILTER DESIGN Soh Ping Jack Sabarina Ismail