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Where To Find This Example

AWR Version 14

Understanding AWR .emz Files

AWR Version 13

This example was renamed since the previous version. Please see Previous Example Page for the version 13 page.

Design Notes

Group Delay Optimization

This example demonstrates the use of output equations in setting up an optimization of a bandpass filter in which the group delay variation across the passband is minimized.

Overview

Three different methods of calculating the flatness are described:

1.  Find the min and max group delay in a band, subtract to get delta between them.

2. Calculate a normalized group delay relative to the center frequency group delay.

3.  Compute the derivative of the group delay with respect to frequency.

Though this example uses group delay, these methods can be used in the flatness optimization of any parameter (ie: gain vs. frequency, voltage vs. time, etc.) All of the calculations are described in the Output Equations window. If you bring up the tune window and tune on the circuit parameters, you can see how each flatness calculation responds differently.

Optimization

For the example, the optimization goals enabled are for the insertion loss, return loss and the group delay from the first method listed above.  The other two methods for group delay optimization have optimization goals but they are disabled.   You can see this from the Optimizer Goals section of the project manager.   You can enable or disable any goals you want to see how the affect the optimization in this project.  

Schematic - Bandpass

Graph - Method 2 Normalized Group Delay

Graph - S Parameters

Graph - Method 3 Group Delay Derivitive vs Freq

Graph - Method 1 Group Delay Min and Max