Virtuoso AMS Environment User Guide

Using Test Fixtures

Creating and Using a Textual Test Fixture

A schematic test fixture is structural only, instantiating the top-level module, analog stimuli, and analog sources that deliver analog stimuli. However, the approach described here uses textual test fixtures. Textual test fixtures often include behavioral code along with whatever instantiations are required.

Either approach assumes that you have a top-level view of the design to be tested. For example, the top-level view might be a VHDL or Verilog-AMS text module. Or the top-level design might be a schematic with, for example, hierarchical connectors that represent the pins of an integrated circuit. AMS Designer netlists schematics into Verilog-AMS modules so, in either case, the task ultimately becomes one of instantiating a textual module in the test fixture.

Test fixtures vary according to the kind of high-level view being tested and according to the different practices of designers. The test fixtures described in this chapter contain both structural and behavioral code.

Creating a Textual Test Fixture

Most of the steps involved in creating a textual test fixture are the same as those used to create any other text module. However, the contents of the module reflect its position as the highest module in the hierarchy. You can create the test fixture either inside the AMS environment or outside of the environment.

You can use any of the AMS Designer supported languages for a test fixture, but differences in the way the languages are supported might tend to push you to one language in preference to another. The examples in this chapter use Verilog-AMS.

■To create a Verilog-AMS test fixture inside the AMS environment,

a.Select File – New – Cellview from the menu in the CIW.

b.In the Create New File dialog box, choose VerilogAMS-Editor in the Tool field.

c.Choose the library to hold the test fixture.

d.Type in the cell name and view name to be used for the test fixture. Remember that the cell name must be the same as the module name that you plan to use.

e.Click OK.

f.In the editor window that appears, compose the test fixture module. Save it when you are done.