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Creating a component that allows setting a changing value on a bus in a single transient simulation

Yuto Lau

Hi everyone,

The cell "bussetp" introduced in the link below works pretty well, if the bus value is static in transient simulation.

https://support.cadence.com/apex/ArticleAttachmentPortal?id=a1Od0000000nX1lEAE&pageName=ArticleContent

In some transient simulation, we would like to define the "bus value" as different value at time points in a single transient simulation.

e.g. t1=10ns, bus_value=3; t2= 30ns, bus_value=5, t3=60ns, bus_value=2,...

Is it possible to edit the script to support above data set?

I see there is "pwl" option in "vcvs". Is it similar to "pwl" in "vsource"?

Can we define parameter "busvalue" as a vector, and then put the vector as value of "pwl"?

Thanks and regards,

Yutao

Parents
  • Andrew Beckett

    Yutao,

    That's one of my articles (I created bussetp). Whilst you could use the transient dynamic parameters to change the bus_value at different times, I wouldn't recommend that as there would be no option for a transition time and so you'd end up with an instantaneous change in value, which is likely to cause convergence difficulties. I also think that trying to use the PWL option of vcvs is not going to be the way to handle this.

    Rather than using bussetp, I would suggest using the Vector File input on Setup->Simulation Files in ADE. A vector file allows you to define time-value pairs for a bus, together with the high and low values, the rise time etc. This is documented in the Spectre Classic Simulator, Spectre APS, Spectre X, Spectre XPS, Spectre FMC
    Analysis, and Legato Reliability Solution User Guide in an appendix (Appendix D in current versions) Digital Vector File Format. You can find this online or in your Spectre installation at <SPECTREINSTDIR>/doc/spectreuser/spectreuser.pdf

    Andrew

  • Yuto Lau
    in reply to Andrew Beckett

    Hi Andrew,

     I will take a look at the Vector File.

    By the way, why PWL option in vcvs is not an option?

    What is PWL option in vcvs for actually? I have thought that it is used to defined time-value pair for gain.

    Regards,

    Yutao

Reply
  • Yuto Lau
    in reply to Andrew Beckett

    Hi Andrew,

     I will take a look at the Vector File.

    By the way, why PWL option in vcvs is not an option?

    What is PWL option in vcvs for actually? I have thought that it is used to defined time-value pair for gain.

    Regards,

    Yutao

Children
  • Andrew Beckett
    in reply to Yuto Lau

    Yutao,

    The pwl option for vcvs defines voltage-voltage pairs (not time-voltage pairs). It defines the input voltage to output voltage mapping of the controlled source (with interpolation between the points). It won't do what you want.

    Andrew

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