Sonnet User's Guide - Sonnet Software

Sonnet User’s Guide
Upon the completion of creating your Broadband model, you should open the
original project in the response viewer, then add the predicted S-parameter data
file to your graph and compare the two responses. If you are creating your Broadband
Model in the response viewer, you may do this automatically by clicking on
the Plot button in the Broadband Spice Details dialog box which appears upon
completion of your model. Use the log information in the Details window, which
is detailed in the next section, to determine which parameter had the highest error
and any critical parameters whose error was greater than 0.1%. Check these parameters
to see how much the curve fit data varies from your circuit response.
If your Broadband Spice Model is to be used for a transient analysis, be aware that
the frequency response of the model up to 1/T where T is the minimum time step
of the transient analysis is important. You should use the Advanced Broadband
Model options dialog box to specify additional predicted data up to 1/T. You access
this dialog box by clicking on the Advanced button in the Broadband Model
File entry dialog box in the project editor or in the Output Broadband Model dialog
box in the response viewer. This allows you to view the frequency response of
your model at data points not included in your em analysis. You should look for
anomalies in the response that indicate a problem with the model, such as S-parameters
greater than one or unexpected sharp resonances.
You may also use the stability factor in order to ensure a stable transient analysis.
Please see "Broadband Spice Extractor Stability Factor" on page 327.
If the model is not accurate enough, see “Improving the Accuracy of the Broadband
Spice Model,” page 326 for suggestions on improving your Broadband
Spice model.
Broadband Spice Extractor Log
The Broadband Spice Extractor log, displayed in the Broadband Spice details window,
contains detailed information about the creation of your Spice model file.
You may view a summary of the log or the complete log. To view the summary
of the log, click on the Summary button at the bottom of the window. To return to
the full log, click on the Complete button.
You use the log to determine which parameters to examine in order to determine
if the Spice model is accurate enough for your use. Two log files are shown below,
the first log is for a model which achieved the error threshold and the second log
324