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Parameterizing PSP model card parameters, for ADE parametric Analysis

araol

Hello,

If I am using a PSP model in Virtuoso. I have a .scs model file under Spectre>models, with a bunch of model parameters. Am I able to parameterize those model card parameters, so that I can run parametric analysis in ADE? 

For example, this PSP model has a kvt mis-match parameter. Currently, if I want to study the effect of the kvt parameter in current mirror mismatch, as an example; I have to open the FET .scs file each run and change the model parameter value and then re-run my current mirror ADE simulation. 

However, I am curious if it's possible to make that PSP .scs model card parameter (e.g. kvt), a variable I can run parametric analysis on. Like how I might do parametric analysis on gate length.   

Hopefully this was clear? Thanks.

Parents
  • Andrew Beckett

    You can edit the model file, make the kvt parameter value some variable name, and then add that as a design variable in ADE and sweep it.

    Andrew

  • araol
    in reply to Andrew Beckett

    Hi Andrew, thanks for your suggestion. 

    I tried to make the kvt parameter in the .scs file a variable. And then in the ADE XL editor, I added that design variable. I ran monte carlo analysis (ADEXL) on a simple nmos testbench, to get it's DC operating point and see how the Std Dev of OP(.... "vth") will change with different kvt values. In the image below - to the right is the psp .scs file for my FET, and to the left is the ADE XL editor where I included that kvt design variable.

    When I change the kvt_var design variable in the ADE XL editor, my Std Dev does not change in the .mc run. However, when if I manually edit the kvt parameter in the .scs file direclty. Then I see a change in Std Dev from the .mc run. So, I know that changing the parameter in the .scs file will effect my Std Dev result. But what I am not understanding/doing properly is turning that kvt parameter into a variable. So is it possible, and how do I make that kvt parameter a design variable which I can then use for parametric analysis ? 

    I haven't been able to find others who have done this. This post from 8 years ago indicates it's not possible? but this was 8 years ago: How to do a parametric analysis for a model parameter ?

    Thanks

Reply
  • araol
    in reply to Andrew Beckett

    Hi Andrew, thanks for your suggestion. 

    I tried to make the kvt parameter in the .scs file a variable. And then in the ADE XL editor, I added that design variable. I ran monte carlo analysis (ADEXL) on a simple nmos testbench, to get it's DC operating point and see how the Std Dev of OP(.... "vth") will change with different kvt values. In the image below - to the right is the psp .scs file for my FET, and to the left is the ADE XL editor where I included that kvt design variable.

    When I change the kvt_var design variable in the ADE XL editor, my Std Dev does not change in the .mc run. However, when if I manually edit the kvt parameter in the .scs file direclty. Then I see a change in Std Dev from the .mc run. So, I know that changing the parameter in the .scs file will effect my Std Dev result. But what I am not understanding/doing properly is turning that kvt parameter into a variable. So is it possible, and how do I make that kvt parameter a design variable which I can then use for parametric analysis ? 

    I haven't been able to find others who have done this. This post from 8 years ago indicates it's not possible? but this was 8 years ago: How to do a parametric analysis for a model parameter ?

    Thanks

Children
  • Andrew Beckett
    in reply to araol

    The post you reference (the second answer from Shawn) indicates that it can work - the response from Quek was specifically stating about string parameters (not sure why it says that, since the original post didn't mention strings, but perhaps it was edited). Even then you can certainly sweep string parameters (maybe you couldn't at the time, but it's worked for many years).

    I don't have enough information to go on with your description above - I can't see the whole setup and understand if if there's any mistakes.

    I suggest you contact customer support - there's no reason why this shouldn't be possible and should work. This is not that unusual - many have done this (as have I). A number of PDKs are even set up to allow you to vary certain model parameters this way.

    Andrew

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