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Performing Monte-Carlo simulation with AMS

Svilen64

Hi,

I am relatively new to working with AMS. However, I have a design with a digital block that if simulated with its schematic view with spectre, takes a week to finish. Substituting the digital with its RTL and running AMS takes just a few hours. I have run transient simulation this way and it runs ok, I can get the results from the expressions I have defined.
I wanted to also run MC with AMS (and ICRP mode) and here I was not very successful. I use the same testbench as for the transient AMS simulation, just choose the MC setup and also the ttg_localmismatch models. However simulation itself produces pretty much garbage. and as a result also the expressions don't evaluate. For ex, I have a verilog file generating stimuli for the test bench. In MC sims, all outputs of that block are 0, while they are as they should be when running just regular transient simulation with AMS.

I was wondering if there is anything different I should set up for the MC simulation now, when I am using the AMS - different, I mean, compared to non-AMS simulations? Is it at all possible to run MC with AMS?

Thanks
Svilen

Parents
  • Andrew Beckett

    Svilen,

    This should work without you needing to do anything special. Running AMS with Monte Carlo is absolutely possible and supported. 

    Andrew

  • Svilen64
    in reply to Andrew Beckett

    OK, that's a relief. Any suggestions how I should figure out why when I turn on MC and the system verilog stimuli block produces all 0 for its outputs?

Reply
  • Svilen64
    in reply to Andrew Beckett

    OK, that's a relief. Any suggestions how I should figure out why when I turn on MC and the system verilog stimuli block produces all 0 for its outputs?

Children
  • ShawnLogan
    in reply to Svilen64

    Dear Svilen64,

    Svilen64 said:
    Any suggestions how I should figure out why when I turn on MC and the system verilog stimuli block produces all 0 for its outputs?

    I have a couple of thoughts if you are still interested and are motivated to experiment...perhaps you have already tried one or more of these!

    1. Is the output of the system verilog stimuli block identically 0 if you check the "Nominal Corner" in Figure 1 and examine the transient output of the system verilog block for the "Nominal Corner"?

    Figure 1

    2. If you run a Monte-Carlo simulation with only the nominal corner (i.e., no mismatch induced variation nor process variation), are the outputs from your stimuli block still identically 0?

    3. Have you tried to exclude any variation in the system verilog block in your Monte-Carlo simulation? I have shown an example of the GUI in Figure 2 where I list 4 instances of a veriloga block that I want to exclude any variation.

    Shawn

    Figure 2

    Just a few thoughts...

    Shawn

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