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CDF

syafiq

Hello,

I have a question here. Can I pass the model parameter (e.g: vth0, u) using CDF?

If yes, can you let me know how to do it? Currently, I am able to pass the parameter such as width and length. But not the model parameter.

The reason being is because I wanted to evaluate the impact of different vth0 in my design. And I want every instance to have unique vth0.

Thanks

Syafiq

  • If your model uses BSIM parameters to structure your device, then no.

    Unless you have a custom active device spectre model with a defined vt0 (highly doubt there would be PDK with Vt0), you can use CDF to pass Vth,

  • Actually it is possible, but you'd have to rewrite your models to allow the parameter to be passed in. For example, you'd need to create your models like this:

    inline subckt nch (d g s b)
    parameters w=1u l=1u ... vt0=0.7 // or whatever you want
    nch (d g s b) nch w=w l=l ...
    model nch bsim4 type=n \
    ...  \
    vt0=vt0 ... // can't remember whether the model parameter is called vt0

    ends nch

    Check the names of the model parameters using "spectre -h bsim4". Anyway, having created this inline subckt wrapper around your device model where you've parameterised one of the model parameters, you can then add a CDF parameter to your component using Tools->CDF->Edit CDF and get it to netlist that parameter too.

    However, I'm not entirely convinced of the usefulness of such an exercise! Presumably in reality you don't have control over the model parameter on an instance by instance basis... (or even at all, given that it's controlled by the manufacturing process).

    Kind Regards,

    Andrew.

  • I have never seen any PDK (so far) explicitly using vt0. Unless it's an ideal model used for system behaviorial modeling.A rudimentary model could be found on Prof.Razavi's website - 

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