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In a tran sim, first sim subset of schematic then sim whole schematic

sray

Hi,

I am using Spectre in conjunction with ADE XL.

Spectre: 15.1.0.679.isr14

Virtuoso: IC6.1.7-64b.500.8

I am wondering if the following is possible: in a single transient simulation of duration T, from t=0-->t* simulate a subset of the schematic, then from t=t*-->T simulate the entire schematic.

What I'm imagining, informally, is starting the sim with an instance in the schematic de-netlisted, then at t=t* un-de-netlisting that instance. I'm aware of the "dynamic parameter" feature where, for example, at t=0 errpreset can be set to liberal, and then at t=t* errpreset can be set to conservative. In this spirit, I'm wondering if something like a "dynamic netlist" is possible.

Thanks,

Subhajit

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  • ShawnLogan

    Dear sray,

    There are a number of parameters that can be changed during a transient analysis as detailed in the link:

    https://support.cadence.com/apex/ArticleAttachmentPortal?id=a1Od0000000nSoyEAE&pageName=ArticleContent

    This list includes a lot more than just the errpreset options.

    However, to accomplish what I believe you are describing suggests the netlisting process must be repeated at some time t = t*. I would imagine you might accomplish you objective by using some switches to disconnect the power and inputs/outputs of the subcircuits of interest for t< t*. At t = t*, you woke enable their power and inputs.outputs. Of course, this will keep the same number of nets in your circuit for the entire span of the simulation. However, the impact on simulation time of the subcircuit(s) that are disconnected or powered-down might not be too great as their nodes are quiescent.

    Is this methodology something you think might be worth considering?

    Shawn

  • sray
    in reply to ShawnLogan

    Hi Shawn,

    Thanks for the link. I hadn't realized there were so many other parameters that can be dynamic parameters. In particular, the "isnoisy" parameter being dynamic seems especally useful.

    Nice suggestion--using some switches to simply power down the subcircuit that I would've otherwise wanted de-netlisted will surely speed up the sim somewhat, as you explained. I'll give it a try.

    Thanks,

    Subhajit

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  • sray
    in reply to ShawnLogan

    Hi Shawn,

    Thanks for the link. I hadn't realized there were so many other parameters that can be dynamic parameters. In particular, the "isnoisy" parameter being dynamic seems especally useful.

    Nice suggestion--using some switches to simply power down the subcircuit that I would've otherwise wanted de-netlisted will surely speed up the sim somewhat, as you explained. I'll give it a try.

    Thanks,

    Subhajit

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