Using the Models

There are five models available: Touchstone S-Parameters, Spectre S-Parameters, Broadband Spice, N-Coupled Line and Inductor. The five types of models are handled in a very similar manner so that the ensuing discussion applies to all types of models.

When you specify any model, a schematic view of the model and a symbol for the model are created. The symbol can be a layout look-alike (default) or a black box. To view the model, select Models ⇒ <Model Type> ⇒ Show View to open a view of the schematic, the symbol and the View <Model Type> Model dialog box. An example is shown below. The “Add Ref. Pin” option was selected in the Model Symbol Options dialog box, so that a reference pin appears in the schematic.

The View Model dialog box, which appears when you view the model, provides information about the model including the name of the symbol view and the model view.

For all models, the Symbol view is automatically created along with the model. You use the symbol view in your schematic design. You plug in the symbol created by the Cadence Virtuoso Interface so that the S-parameter model or Broadband Spice model will be used in the Cadence simulation.

In order to use a model in the Analog Design Environment, it is recommended that you create a config view which references the Sonnet symbol. This is because when you create multiple models from an analysis, only one symbol is created and shared among all of the models. The configuration view allows you to easily switch which model the symbol is representing. To set up the environment to use your model, do the following:

1. Create a test bench schematic using your Sonnet symbol.
   
   An example is shown below, using a layout look-alike symbol.
   
   
2. Create a Config view based on the test bench schematic.
   
   When you create the Config cell use “config” as the view.
   
   
3. In the Hierarchy Editor for the Config view, enter the model you wish the symbol to point to under View to Use for the cell view from which the test bench was created, then save the Config cell.
   
   An example, with schematic-sonnet-cds-param entered as the model, is pictured below. To change what model the symbol references, you would simply edit the config view.
   
   
4. Select Tools ⇒ ADE L from the main menu in the CIW.
   
   The Virtuoso Analog Design Environment window appears on your display.
   
   
5. Select Setup ⇒ Design from the main menu of the Analog Design Environment.

The Choosing Design dialog box appears on your display.

6. Select the Library and Cell you wish to use and select “config” for the view, then click OK.

When you choose the Test bench Cell name, the View Name should be set to config, as shown above. When you close the dialog box, the title bar of the Analog Design Environment window is updated with the Cell you have chosen.

The model is loaded and ready to use in your simulation.

Using the Symbol Model Utility