Need help on forward body biasing!!

dick_freebird said:

I am not a fan of this. Yes, you can lower the "effective VT"
by about 0.6V/V. But you also are forward-biasing the
parasitic BJT base, and even if you don't "quite" get to
elevated DC drain current you are pushing further into
substrate noise amplification.

Now with that low a VDD, maybe you can't light it up
and don't care.

I would suggest using a replica feedback bias scheme
to servo body voltage to "what you want from the FET".
If it's zero VT(1uA) then you put a G=0, S=0, B=amp
output, D w/ 1uA load = amp feedback replica device
in a control loop and hope for chip-wide matching.

But if you don't need that last couple octaves of speed,
you could just design in subthreshold and take what
comes, at much less complexity / risk.

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