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VerilogA simulation error

TUKA

Dear all,

I am facing an error in a verilogA model simulation.

I have a transfer function in the form of

I have modelled it using the statement:

   V(Vout) <+ laplace_nd(V(Vin), {A,0}, {C,B});

But in my case, A, Band C are variables, whose values are computed depending on the real parameters I set.

Is it true that the simulator does not allow us to have variable expressions inside laplce_nd function? If so, any other possible approach to resolve this issue?

Thanks and regards,

Tuka

  • ShawnLogan

    Dear TUKA,

    TUKA said:
    Is it true that the simulator does not allow us to have variable expressions inside laplce_nd function?

    I will not pretend to be a verilog-A expert (or even a novice!), but it appears this is stated in the verilog-A Language Reference Manual (Product Version 21.1, January 2023)on page 193, where it states "You cannot use array values defined by variables."

    TUKA said:
    If so, any other possible approach to resolve this issue?

    There is an example of a means to use an array variable within the laplace_nd() function on the top of page 196 of the verilog-A Language Reference manual. Please download the manual from URL:

    https://support.cadence.com/apex/techpubDocViewerPage?path=veriaref/veriaref21.1/veriarefTOC.html

    I hope this is helpful TUKA!

    Shawn

  • TUKA
    in reply to ShawnLogan

    Dear Shawn,

    Thanks a lot for getting back to me.

    Sure, I will check and follow the Verilog-A Language reference manual. Thanks a lot for mentioning the corresponding page numbers and the download link for the URL.

    Regards,

    Tuka

  • Andrew Beckett
    in reply to TUKA

    It's OK (using the method shown in the documentation) to have the coefficient arrays computed during the initial_step - even if that involves intermediate variables to compute from constants and parameters. What you can't do is have the coefficients changing over time.

    Anyway, the references that Shawn gave will give you the information. You can also look at this manual by running <SPECTREinstDir>/bin/cdnshelp or looking in <SPECTREinstDir>/doc/veriaref/veriaref.pdf - it's in your software installation.

    Regards,

    Andrew

  • TUKA
    in reply to Andrew Beckett

    Dear Andrew,

    Thank you for your feedback.

    Sure, I will follow the manual provided in the software installation.

    Regards,

    Tuka

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