2-state fully differential op-amp compensation

[asnprabhu]

Can you explain me the poles and zeros that exists

 

[gingerjiang]

do you mean a 2-stage fully differential op-amp? what is your amplifier architecture? which type compensation?

 

[asnprabhu]

I'm talking abt 2-state fully differential op-amp with Resistor and capacitor compensation. these R and C are used between stage 1 and stage 2

where in capacitor is used for pole compensation, and resistor for pushing the zero to infinity.

I remember this but if u know more details abt his can you explain?

 

[gingerjiang]

dominant pole is -1/(gm2*r2*r1*cc);

secondary pole is -gm2*cc/(c1*c2+cc*c1+cc*c2);

another pole is -1/(rz*c1);

zero is 1/(cc*(1/gm2-rz)).

in general, make secondary pole and zero equal, so we get good phase margin

(cc compensation capacitor, rz nulling resistor)