Broadband Spice Advanced Options dialog box

Project Editor - Broadband Model File Entry dialog box   Response Viewer - Output Broadband Model File dialog box

The Broadband Spice Advanced dialog box is opened when you click on the Advanced button in the Broadband Model File Entry dialog box. This dialog box allows you specify additional frequency points used to test the stability of the model and to limit the complexity of the broadband model. You may also specify an output file of the predicted S-Parameter data. See below for a detailed discussion of the controls.

Predicted S-Parameters

Override default additional frequencies:  In order to test the stability of the model, extra frequencies outside of the original analysis band are calculated as part of the predicted data. By default, these extra frequencies start at the highest frequency of your original analysis and stop at  three times this value, with a step size set to the last step size of your original analysis. Select this checkbox if you wish to specify a different set of extra frequencies to be calculated from the model and used to test stability. Selecting this checkbox enables the Start, Stop and Step text entry boxes below.  If you wish to specify only one additional frequency, enter that frequency in the Start text entry box. Otherwise, Start provides the beginning frequency, Stop the ending frequency and Step the spacing. All predicted data is written to a data file if the Write data file checkbox (see below) is checked.

Write data file: Selecting this checkbox creates a file which contains the predicted S-parameter data produced by the rational polynomial used to generate the Broadband Spice model. The filename to which the predicted data is written appears just below and may not be changed. This file is created in the same directory in which the output Spice model file is created. This file allows you to visually inspect how close a fit your broadband model is to your source data.

For more information, see the "Checking the Accuracy of the Broadband Spice Model" section in the Spice Model Synthesis chapter in the Sonnet User's Guide.

Limit Modeling Band

Lower Limit: By default, the full range of analysis data in the project is used as input to create the Broadband model. If you wish to limit the data used to create the model, enter the lowest frequency you wish to use in this text entry box. Any lower frequencies contained in the analysis data will not be used as input. If no value is entered, then all of the analysis data up to either the Upper Limit, or to highest frequency in the analysis data, is used as input.

Upper Limit: By default, the full range of analysis data in the project is used as input to create the Broadband model. If you wish to limit the data used to create the model, enter the highest frequency you wish to use in this text entry box. Any higher frequencies contained in the analysis data will not be used as input.  If no value is entered, then all of the analysis data from either the Lower Limit, or from the lowest frequency in the analysis data, is used as input.

Total Order

Maximum Order: Enter the desired maximum order of the rational polynomial which produces the Broadband Spice model here. This entry may be used to limit the complexity of the model. The default value is 40.

Additional Options: This field should only be used at the direction of Sonnet support personnel.