Design and implementation of a rail-to-rail operational amplifier for photoelectric detection

Photoelectric detection circuit is widely used in fluorescence temperature measurement, optical communication and other fields. In this thesis, a rail-to-rail operational amplifier for photodetection is designed based on a 0.18 um CMOS process. The operational amplifier input stage adopts complementary differential input pairs to provide rail-to-rail common-mode input range, and adopts a folded common-source common-gate structure to improve the gain of the input stage, so that it can realize linear amplification over the entire input voltage range, and can efficiently process the weak signals from photodetector devices. Signals from photodetector devices can be handled efficiently. The output stage of the operational amplifier is a Class AB output, which can drive large loads and provide a rail-to-rail output voltage range. Simulation results show that the low frequency gain of the amplifier is 153 dB, the input offset voltage is 1.7 uV, and the bandwidth is 8.4 MHz under the condition of 3.3 V supply voltage and $25^{\circ} \mathrm{C}$. The operational amplifier has a wide input range, high gain, low input offset voltage and wide bandwidth, and its performance has been verified by tests. The results show that the rail-to-rail operational amplifier design can effectively improve the signal processing capability of the photoelectric detection system, and provide reliable technical support for practical applications.