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Monte_Carlo simulations

fanju

Hello, all. I would like to ask a question concerning how to make a monte_carlo simulation.


In fact, I have created a component model using Verilog-A(model.va). And in the document “.scs”, I have maken some modification.


library setwei

section tm

inline subckt set_model ( d s g b )

//

parameters Cr=0.16a Cl=0.16a Cgs1=0.1a Cgs2=0.1a qe=1.6E-19 Rr=90e3 Rl=90e3 k=1.38E-23 T=300

//

set_model ( d s g b ) SETwei Cr=Cr Cl=Cl Cgs1=Cgs1 Cgs2=Cgs2 qe=qe Rr=Rr Rl=Rl k=k T=T

//

model SETwei SET_Wei

[1]

ends set_model

// ----------------------------------------------------------------------

endsection

Everything is ok to do the normal simulation to see the performance of this component (that is the model writed by verilog-a)


Now i would like to do some monte_carlo simulation. If I add some parameters in the region [1] to do monte_carlo simulations. How should I modify the verilog-a model to recogenise those parameters? or what should i do to realize the monte-carlo simulation (I know that I have to modify the document “mecanism.scs”)

  • Hi

     If you want to perform Monte Carlo simulations using spectre you  will need to add a "statistics" block to describe distribution. Unfortunately, statistics blocks cannot be added to subckts. So you will need to set the statistics block outside of the subckt definition and pass the randomly generated parameters values using different parameter names.

     For example, for the Cr parameter, I added the cr_ext parameter as shown below. One can add multiple vary lines within the process{} block for additional statistical parameters.

    library setwei

    section tm

    parameters cr_ext=0.16a // nominal value
    statistics {
            process{
                 vary cr_ext dist=gauss std=0.04a
            }
    }

    inline subckt set_model ( d s g b )

    //

    parameters Cr=cr_ext Cl=0.16a Cgs1=0.1a Cgs2=0.1a qe=1.6E-19 Rr=90e3 Rl=90e3 k=1.38E-23 T=300

    //

    set_model ( d s g b ) SETwei Cr=Cr Cl=Cl Cgs1=Cgs1 Cgs2=Cgs2 qe=qe Rr=Rr Rl=Rl k=k T=T

    //

    model SETwei SET_Wei

    [1]

    ends set_model

    // ----------------------------------------------------------------------

    endsection

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