I am simulating Folded cascode opamp and when I am doing AC analysis the phase and agmitude graph is coming opposite, that means when i am takine 20dB Gain (Vout/vin) then it is showing opposite graph with negative values. but when i am doing 20dBGain(Vin/Vout) it is coming properly. I am not getting what is the problem. Please help.
I doubt anyone could help you without some more details. Most likely your circuit is not really working - it sounds as if it is attenuating rather than having gain. Maybe your DC operating point is incorrect?
You are doing a loop stability analysis on the opamp connected in unity gain buffer mode I presume?
If this is the case then reverse the polarity of the lstb voltage source probe you are using.