surianova said:
ya, i am using folded cascode for the amplifier. How to eliminate this peaking or zero?
It is very difficult to eliminate the peaking. Fow low frequency application, you can change to miller compensation tu push the peaking far beyond the GBW. Fow high frequency application, it is profer to choose PMOS as differential pairs and NMOS as output device. Since the cascode device is NMOS transistor which has larger gm than PMOS ones, it maybe helpful for reduce the peaking in frequency response.
The following attachment will help you. Good luck!
sixth