Start Your Engines: Optimizing Mixed-Signal Simulation Efficiency

Cadence Spectre AMS Designer is a high-performance mixed-signal simulation system. The ability to use multiple engines and drive from a variety of platforms enables you to "rev up" your mixed-signal design verification and take the checkered flag in the race to the market. The Start Your Engines blog series will provide you with tips and insights to help you tune your simulation performance and accelerate down the road to productivity.

In a traditional mixed-signal circuit design and simulation, the mixed-signal design comprises analog and digital design blocks. When running a simulation, analog and digital engines run simultaneously from the beginning to the end, with signals synchronized on the boundary. During the simulation, the analog engine usually dominates the simulation time and resources. If you need to run multiple tests of the same circuit with different stimuli or test patterns, then you need to run the simulation multiple times.

Spectre AMS Designer provides two advanced technologies to help you improve the efficiency of your mixed-signal designs and increase the simulation speed.

The first method is turning off the analog engine. This feature allows designers to turn the analog engine on or off in a mixed-signal simulation for a time window when the analog circuit function is not necessary during simulation. Turning off the analog engine can significantly speed up the simulation time when only the digital engine is running.

In Spectre AMS Designer, there are both TCL commands and system tasks for designers to control when to turn the analog engine on or off. System tasks can be placed in a testbench and conditionally controlled by design signals. This is an easy-use model and gives the most flexibility.

The second method uses the Process-Based Save Restart (PBSR) flow, which lets you save a snapshot of your design at a certain time point and then allows multiple users to load the same snapshot. This snapshot can be run with different stimuli or test vectors. Reusing the same initial stage of the design can reduce a lot of redundant costs of time and resources for simulations.

Spectre AMS Designer also provides multiple TCL commands to let the design force or release both analog and digital node values and to change simulation parameters. Using these commands and the testbench behavior, a designer can run multi-test simulations without repeating the initialization for every run.

To learn more about these methods, please refer to the latest version of the Spectre AMS Designer and Xcelium Simulator Mixed-Signal User Guide or contact your Cadence Customer Support team.

Related Resources

For more information on Cadence circuit design products and services, visit www.cadence.com.

About Start Your Engines

The Start Your Engines series brings you blog posts from several analog/mixed-signal subject matter experts on a variety of topics, such as introduction to the new features in AMS Designer, tips for enhanced working with existing features, and much more. To receive notifications about new blogs in this series, click Subscribe and submit your email ID in the Subscriptions box.

- Qingyu Lin