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parameterize voltage source in Virtuoso

gnaw
Hi,

I would like to model the following parametric equation using vpulse in Cadence Virtuoso,version IC6.1.5.500.10:

V(t)=p*exp(-t^(k-5)/p)*t^(k-5) where p,k and t are variables.
Can anyone tell me how I can use the Cadence system time in the above equation? I tried to use "run a parametric analysis simulation in Cadence Virtuoso and it plotted many graphs(according to the size of t). For example, when I set the simulation stop time to 60ps, the simulation gives 60 different graphs of V(t). Is there any efficient way to come up with only one graph for V(t) using Cadence Virtuoso?

Thank you.

  • You could do this with a VerilogA model, or you could use a bsource.

    Create a file, vexp.scs, with this content:

    inline subckt vexp (P N)
      parameters p=1 k=6
      vexp (P N) bsource v=p*exp($time**(k-5)/p)*$time**(k-5)
    ends vexp

    Create a symbol with two terminals (maybe you could copy the vsource symbol and spectre view from analogLib), and then delete the Base CDF (from the Tools->CDF menu). Create two CDF parameters, p and k, of type string with parseAsCEL and parseAsNumber set to "yes". In the CDF simulation information for spectre, set the termOrder to be "P N" and the instParameters to be "p k" and the componentName to be "vexp".

    Or you could create a VerilogA view - this might be easier - which contains:

    `include "disciplines.vams"
    module vexp (P,N);
    output P,N;
    electrical P,N;
    parameter real p=1;
    parameter real k=6;

    analog
      V(P,N)<+p*exp($abstime**(k-5)/p)*$abstime**(k-5);
    endmodule

    You'll then be prompted to create a symbol, and the CDF will be created for you.

    Regards,

    Andrew.

  • Thanks a lot, Andrew!

    This is my first time to use Cadence community. It is so helpful. I am very impressed by such a short turn-around time. 

    Thanks again.

     

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