Excuse me, when I simulation my amp,I find vgs-vth=20mv,vdsat=38mv.gain=40dB
1.Does this means the mos is in moderate inversion?
2.vdsat is so small,whether it will have any bad impact on my amp?
According to Binkley (s. below), regarding to the very low vdsat=38mV info (above), it could well be in weak inversion mode. Actually, vdsat shouldn't be lower than 4Vt≈100mV (at room temperature).
According to Binkley (s. below), regarding to the very low vdsat=38mV info (above), it could well be in weak inversion mode. Actually, vdsat shouldn't be lower than 4Vt≈100mV (at room temperature).
Should you mean VDS,sat, there would be none, but theoretically it doesn't seem possible - at least at room temperature or above. But of course VDS,sat depends on its calculation method, i.e. the boundary condition used for it.
Don't mix up the drain-source voltage Vds with the saturation voltage VDS,sat ; Vds may of course be lower than 100mV, it can be zero or even negative - depending on its external circuit.
From what I gather from forum posts and discussions with colleagues, (and as erikl said) there is no harm in operating in weak inversion/subthreshold region (also see: https://www.edaboard.com/threads/355783/)
I will try to find that. I am not sure which book. However, you can see the similar one from post #4 here by erikl.
According to this, the transistor in original post (Veff = Vgs - Vth =20mV) should be in moderate inversion.