I tried to do a monte carlo analysis of the opamp that I have designed. I ran the simulation for 100 samples with matching and process, suprisingly the results I get are very bizare. I have gains that are not even 1 dB which is something I completely dint see with a normal corner/process variation . I know that the reason for this bizare result is that the simulation takes mismatch into account(shown in image below with the configured simulation).But my main question is how can I improve this result keeping my design as it is ? IS there a way through which I could tune my MOSFET dimensions such that I have imrpoved results ?
Simulation results with mismatch included as shown in the simulation configuration.
Simulation result without mismatch but with only process.
Circuit diagram, with the resistor divider being the outputs from the bandgap reference.