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Monte Carlo Gauss Std units?

sporre

In order to apply a Gaussian distribution to a device parameter for Monte Carlo simulations, I have to use a line of code such as the following in the model file:

vary vthnmis_rf dist=gauss std=1/1

 This came right out of a real model file from a TSMC process. Can anyone tell me what the units on std are?  vthnmis is a quantity that is added to vt, and it should be in volts.  Standard deviation can't be in volts, so I am not sure what it is.  I know that I want to set it to 50mV.

Thanks

Kyle

Parents

  • Kyle,

    It doesn't make that much sense to me - but I suspect there's some aspect that's missing, and unless I wade through a real example (sorry, bit pushed for time at the moment), I probably can't help much more. Are you looking at the vth0 model parameter in the results database, or are you measuring vth some other way? And are you doing enough points?

    BTW, unless you use the  _mis devices you won't get any mismatch variation - this is the way that that foundry does things for some reason.

    Regards,

    Andrew.

Reply

  • Kyle,

    It doesn't make that much sense to me - but I suspect there's some aspect that's missing, and unless I wade through a real example (sorry, bit pushed for time at the moment), I probably can't help much more. Are you looking at the vth0 model parameter in the results database, or are you measuring vth some other way? And are you doing enough points?

    BTW, unless you use the  _mis devices you won't get any mismatch variation - this is the way that that foundry does things for some reason.

    Regards,

    Andrew.

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