Research of High-Speed and Stable Photodetector of Monolithic Optocoupler Chip

Abstract

Designed and fabricated a monolithically integrated high-speed optical receiver module optocoupler chip, which contains “Nwell-Pepitaxial-Psub” model for the photoelectric detector (PD), the transimpedance amplifier (TIA) and the subsequent processing circuits. Clarify the circuit structure of the TIA and the adjustable gain theory. Detailed analysis the frequency response of the PD models and simulated the PD theoretical analysis. Simulation results showed that when the temperature is constant and the photocurrent change from 5uA to 80uA, the response speed of the PD and TIA module change quickly. When the photocurrent (Iph) unchanged and the test temperature (T) change from -25℃ to 125℃, the delay time does not exceed 10ns. Tape-out with the 1P3M 0.35um BCD process and the test results showed when the T is 25℃ and the Iph is 20uA, the delay time of the whole chip are 155ns and 205ns. When the T is125℃ and the Iphh kept constant, the delay time of the whole chip are 153ns and 220ns.The results show that the photodetector design with high-speed response capability, combined with the TIA gain adjusted in real time, the high-speed monolithic integration optocouplers can be established.