Community Forums Custom IC Design steppreset in .scs file

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steppreset in .scs file

sjwprcker

Hi,

I would like to define steppreset as a dynamic parameter in tran simulation. The sim file is

section XXX
pset_ctrl paramset{
time steppreset
0 mx
8u ax
}
endsection

The error info is

Error found by spectre during hierarchy flattening.
ERROR: Unknown parameter `mx' has been specified in expression `mx'
ERROR: Unknown parameter `ax' has been specified in expression `ax'

The referrence is: https://community.cadence.com/cadence_blogs_8/b/cic/posts/dynamically-changing-spectre-x-solver-settings 

My question is why mx and ax is not accepted?

BR

  • Dear sjwprck,

    sjwprcker said:
    My question is why mx and ax is not accepted?

    Please excuse my comment as it seems it may be obvious and you may have already verified this. In the interest of at lest mentioning it, "steppreset" is a relatively new spectre X parameter and from the article at URL:

    https://support.cadence.com/apex/ArticleAttachmentPortal?id=a1O3w000009fo7PEAQ&pageName=ArticleContent

    it notes:

    "This is possible starting with Spectre 20.1 ISR15 (20.1.0.485.isr15) and. Spectre 21.1. ISR5 (21.1.0.303.isr5)."

    Is the version of Spectre you are using at least Spectre 20.1 ISR15 (20.1.0.485.isr15)?

    Shawn

  • in reply to ShawnLogan

    Actually, the reason is that steppreset is not supported in paramset for use with dynamic parameters yet. There's an enhancement CCR, 2755025, asking for this. You can contact customer support and request a duplicate is filed on your behalf to help prioritize this.

    Regards,

    Andrew

  • in reply to ShawnLogan

    Hi ShawnLogan,

    My spectre version is 21.1.0.664.isr16. I suppose it is quite latest version, which should support the steppreset feature.

    In fact, I have try the steppreset in dynamic parameter of tran sim option. It works. 

    However, when i try to define it in .scs file and load it, then cadence report those erros. 

    Could you share your idea for that?

  • in reply to Andrew Beckett

    Hi Anderw,

    In fact, I have try the steppreset in dynamic parameter of tran sim option. It works. 

    However, when i try to define it in .scs file and load it, then cadence report those erros. 

  • in reply to sjwprcker

    It works when specified that way (which uses param_vec). That's what the article shows. It doesn't work if you use the "Parameter Set" appoach (which uses a paramset, which is what you were trying). The CCR I mentioned is to add support for the paramset approach.

    In fact the reason that steppreset doesn't show in the drop-down list of parameters is because it's not yet supported in the Parameter Set approach - the list of parameters is common to both Parameter and Parameter Set modes and it would then fail if you tried to choose it for Parameter Set mode.

    Andrew

  • in reply to Andrew Beckett

    Hi Andrew,

    Understood. Hopefully cadence could upddate this feature in the near future. 

    Thanks for your clarification.

    BR

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