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implement noise behavior of transistor in spice code in spectre

Bo Yu

Hi,

It's very nice to be here. I got several problems solved by reading the threads here.

But there are some more as is always the case when I try to learn something new.

So I did dc and ac simulation with a very simple common source amplifier (See attached picture.). I used the generic nmos transistor in analoglib and used a model card (level=1, thus mos1 model) for the nmos model. 

Those simulations were successful. 

Further, I want to study the output noise of the circuit. And I would also like to replace the nmos model with RPI polysilicon TFT models.

In the mos1 model, there are no parameters available for noise. The same case goes for poly-Si TFT models. How can I implement the noise model? I want to include flicker noise and channel noise. Some literature suggested writing a spice code to do this. I just don't know how it's worked out in cadence.

Thank you for your time.

Bo

  • Why do you think that mos1 and psitft don't have noise parameters? With spectre (you didn't mention the simulator, but I'm guessing it's spectre):

    from "spectre -h mos1":

    Noise model parameters:
96      noisemod=1        Noise model selector.
97      kf=0              Flicker (1/f) noise coefficient.
98      af=1              Flicker (1/f) noise exponent.
99      ef=1              Flicker (1/f) noise frequency exponent.
100     wnoi=1e-5 m       Channel width at which noise parameters were
                          extracted.

    from "spectre -h psitft":

    Noise model parameters:
100     noisemod=1        Noise model selector.
101     kf=0              Flicker (1/f) noise coefficient.
102     af=1              Flicker (1/f) noise exponent.
103     ef=1              Flicker (1/f) noise frequency exponent.
104     wnoi=1e-5 m       Channel width at which noise parameters were
                          extracted.

    So both support noise parameters.

    Also, what is the sudden interest in the Poly-Si TFT model? You're the second person to ask about it in the last few days. Has somebody set this as an exercise on a university course?

    Andrew.

  • in reply to Andrew Beckett

    Thanks Andrew. I was reading Virtuoso Simulator Components and Device Models Reference, 2015 version. There are noise model parameters for MOS1 but not for psitft.

    What are the possible values for noisemod? Is it that only flicker noise are supported in the model?

    haha...I don't know about the other post...I myself am not working for some university course homework. poly-Si TFT devices are getting better performance. It's time to look for more applications using polySi TFT.

    thanks again

  • in reply to Bo Yu

    First of all, I was going to suggest that looking at a 5-6 year old manual was not the right thing to do, but I see it's missing even in the SPECTRE20.1 version of the model manual. The noise equations are common to many other models, and so I think will work just as (say) the EKV model which does give the equations. I believe noisemod just controls the flicker noise model.

    However, this needs to be corrected in the documentation. Please contact customer support.

    Regards,

    Andrew.

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