how to simulate Vth mismatch in spectre
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how to simulate Vth mismatch in spectre

 
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Guest
Posted: Tue Oct 25, 2005 8:10 am    Post subject: how to simulate Vth mismatch in spectre Reply with quote
Hi guys,

I would like to simulate a simple matched differentail amplifier.
If I am interested in only Vth variation, how can I simulate the
mismatch effect?

I put the dc voltage source (2sigma_vth variation) in series with gate
of + input transistor and put dc voltage source(-2sigma_vth variation)
in series with gate of - input transistor.

Is this way correct?
And usually how many sigma_vth variation are used for mismatch
simulation?

Thanks.

h.s

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John O'Donovan
Guest
Posted: Tue Oct 25, 2005 8:10 pm    Post subject: Re: how to simulate Vth mismatch in spectre Reply with quote
Hi,

If you are using bsim3v3 or bsim4 models, you can use the instance
parameter "delvto" to change Vth for the individual transistors, i.e.

m1 d g s b nmos ..... delvto=2*sigma_vth variation
m2 1 2 3 4 nmos ..... delvto=-2*sigma_vth variation

Regards,
John
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