Re: Is this method OK?
Thanks for your kind comment.
Will the 1u/100u PMOS cause great noise?
The MOS thermal noise equation is 4ktηGm, the Gm of the PMOS is very small, so the thermal noise is small. And the flicker noise equation is K/WLf, the WL of this PMOS is also large, so the flicker noise should be also small.
BTW, the IN+ is a DC bias(or AC ground) of this amplifier, the purpose of my adding this PMOS is to make the voltage of IN+(or the voltage of the 1uF capacitor) more stable.I also think this method is OK, and the simulation also proved it.