Design and Analysis of Two-Stage CMOS Operational Amplifier for Fluorescence Signal Processing

Transimpedance amplifier is an important part of the signal processing circuit in the fluorescent optical fiber temperature sensor to amplify the current signal and convert it into a voltage one. The two-stage CMOS operational amplifier, which can be designed to achieve high gain, high CMRR and low input offset voltage, can be used in transimpedance amplifier circuits. Based on 0.18 $\mu$m CMOS process, a two-stage differential operational amplifier is designed in this paper. The simulation results show that the gain of the reaches 85.5dB, the CMRR and the negative PSRR are both around 90dB. The Miller compensation circuit in the circuit increases the gain bandwidth of the two-stage CMOS operational amplifier and makes the phase margin reach 80°. This paper introduces the circuit principle of CMOS two-stage operational amplifier in detail, and according to the simulation result, this operational amplifier meets the index requirement.