Design of Rail to Rail Operating Amplifier

In our report, based on GSMC 0.13 μm 3.3 V, rail to rail operational amplifier was designed, which achieved the input and output rail to rail swing, and total gain was 85 dB with a 60 degrees phase margin. Because of the use of g_m/I_d, the design was more intuitive, and closer to the actual situation of the circuit. Simulations results showed that the indicators were achieved.