Virtuoso Video Diary: What Are Parametric Sets?

4 Sep 2017 • 4 minute read

Over the past few IC6.1.7 and ICADV12.3 ISR releases, a lot of new and useful features have been added to Virtuoso ADE Explorer and Virtuoso ADE Assembler. An interesting one that recently caught my attention amidst this forever-increasing feature list is – Parametric Sets in Design Variables.

This feature could be a savior if you’re working on a gigantic list of design variables or parameters with sweeps, but don’t want to run all the possible sweep combinations for them. Parametric sets help save time and also provide you the flexibility to run a specific set of variables. To put it in simpler words – when you create a parametric set by combining two or more variables, only a selected set of sweep combinations are created by picking values from the same ordinal position for all the variables or parameters in the parametric set. This reduces the number of design points, thereby, reducing the number of simulations.

On the other hand, when you do not create parametric sets, by default ADE Explorer and ADE Assembler create all the possible sweep combinations by pairing each value of a variable or parameter with all given values of the other variables or parameters.

Let's understand this with the help of an example.

Parametric Sets Versus Normal Setup

Consider the following setup in ADE Explorer where you have three design variables, out of which two variables, cload and rload, form a parametric set.

To quickly take a look at how many points will be simulated when you run the setup above, you can open the Run Preview tab. For this, choose the Run Preview option available in the Simulation menu in ADE Explorer. Click the Refresh button on the Run Preview tab and you will get the following values in the points table:

If you want to check how many points would have run when no parametric set was created between cload and rload, just ungroup the parametric set by right-clicking any variable and choosing Ungroup Parametric Set. Now, go back to the Run Preview assistant and click the Refresh button again to apply the changes you've just made. The points table is updated to display the following points:

It's a relatively longer list (9 points) as compared to the previous one that has parametric set (3 points). We can see that the number of simulations are reduced significantly when you create parametric sets.

Once the parametric set is created, you can perform various tasks on parametric set, for example you can:

Add a new variable to an existing parametric set
Create multiple parametric sets; all will be highlighted in a different color
Remove a variable from a parametric set
Ungroup a parametric set
Enable or disable all parametric sets

How Parametric Sets work in ADE Assembler?

Interestingly, when you create parametric sets in ADE Explorer, they are termed as local parametric sets. Now, you must be wondering why it is so...well, this is because ADE Explorer is a single-test environment and the parametric set you create is applicable only for the currently open test in ADE Explorer.

To give some more rationale to the term local – When you move the test to ADE Assembler, the parametric sets work in the same way as they work in ADE Explorer. But, if any variable present in the local parametric set exists in the Global Variable section as well and you have enabled it there, the test-specific variable value (local value) will be overridden and the global value for that variable will be used. For example, cload in the figure below.

Liked it...Want to Know More

To get a detailed and complete understanding of this feature, you can view the Parametric Sets in Design Variables video available on Cadence Online Support. Click the video link now or visit Cadence Online Support and search for this video under Video Library.

Note: If you don’t have a Cadence Online Support account, you can play the above videos (mp4) natively in Cadence Help when you are using Virtuoso IC6.1.7/ ICADV12.3 (ISR14 or later). In the Cadence Help Virtuoso Documentation Library, look for video titles under Video Demos.

We recommend you to try it out and share your experiences/feedback with us, if any.

Related Resources

Virtuoso ADE Explorer User Guide

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

About Virtuoso Video Diary

Virtuoso Video Diary is an online journal that relays information about Virtuoso videos that are available in the Cadence Online Support Video Library. Hundreds of interesting videos on a wide variety of new and exciting Virtuoso features have already been created. Virtuoso Video Diary brings you direct links to these videos and other related material, on regular basis. Click Subscribe to visit the Subscription box at the top of the page in which you can submit your e-mail address to receive notifications about our latest Video Diary posts.

Ashu Vashishtha