How to perform an **efficient parametric simulation** in Cadence Virtuoso with a ** parametric set **of variables to reduce the simulations eliminating unuseful runs.

To **reduce the number of simulations **when using parametric simulations, we can choose only a set of variable combinations to simulate ONLY a few of them instead of ALL the possibilities.

To **reduce the number of simulations **when using parametric simulations, we can choose only a set of variable combinations to simulate ONLY a few of them instead of ALL the possibilities.

In this case, I have 3 variables with several parameters each. So, the simulator will run **48 simulations.**

The solution is called

“Group Parametric Set”

## How to Make it?

1- Select the set of variables you want to group.

2- Right-click on them and select “Group as Parametric Set”

You can always **undo the changes** by choosing “*Ungroup Parametric Set*”

Note, that the set of parameters are **caught in columns**.

The previous example means that Cadence will run ONLY 4 simulations:

To see it more visual, **open the “Run preview” tab** to have a **nice overview **of the combinations** or set of parameters**. To open the tab go Assembler or Explorer view and then click on “Run Preview”.

If they are not there, **refresh the tab** with the orange-yellow button and you will get something like that:

With the **Run Point Selection checkboxes**, you can select exactly which simulations are going to be run.

You must click on the checkboxes to **enable or disable** individual simulations **points**.

Let’s show another example,

I was designing an **8-bits DCO**. A few times I really want to simulate all the 256 steps, but not always. Maybe 5 to 10 points would be more than sufficient.

In total I have 8 digital variables or parameters with 2 values each, therefore I would have to perform 256 simulations… Woww!

Also, later to put together the full system, **I don’t want to simulate all** the 256 cases,** but ONLY some of them**.

Neither I don’t have the computational power to do it, nor is it a waste of time.

The solution was to use the function “*Group as Parametric Set*” to connect together some parameters. Before b0, b1, b2, b3, b4, b5 b6, and b7 with 256 simulations.

Now with the parameter selection, I can simulate only 10 cases.

I hope this trick will help you to improve your Cadence productivity 🙂

Gabby

thank you! this is what I was stacked with Cadence

Nehad

Dear Alberto,

I hope you are doing great.

First of all, thanks a looooot for the comprehensive information.

Second, I have a question. It is related to the adexl but not to grouping the design variables. I will be really so grateful if you can help me.

I am designing a differential amplifier and I have two similar parameter (in both sides of the diff amp) which I want to sweep on them both under condition that they have the same value.

Would you please help me do this?

Thanks a lot in advance and have a lovely day.

Best regards,

Nehad

Alberto L.

Hello Nehad,

If I understand well, It is pretty easy: you can give the value of both parameters with

the same variable… let’s say “VAR1” and then sweep that variable as usual.Best Regards

Alberto