Aiming at temperature drift characteristics of avalanche photodiode（ APD） in weak optical signal detection system

a closed-loop temperature control method for APD is proposed. In this way

APD

thermistor and TEC are integrated in the same component

deep negative feedback techniques of analog circuit is used to realize closed-loop control of temperature and classical control theory is used to establish mathematical model to optimize PID circuit in ordor to ensure gain stability of APD detection circuit. Experiment show that temperature control precision of APD is within ± 0. 1 ℃

and fluctuation of output voltage is about ± 0. 5 m V

which indicates the design restrains influence of temperature variation on APD gain very well.