Design of APD double temperature compensation circuit with high gain stability

The gain of the avalanche photodiode (APD) is temperature sensitive, which greatly limits the application of APD for the all-weather operation in field. In this paper, a dual temperature compensation circuit for APD that included temperature control and high voltage compensation was designed. The temperature control part uses MAX1978 for APD proportional-integral-derivative (PID) temperature control through thermistor and thermo electric cooler (TEC), so that APD temperature is kept constant in a certain ambient temperature range. According to general diode's temperature characteristics, the high voltage compensation part compensates for the high voltage drift needed to stabilize the gain of the APD when ambient temperature changes, using diode 1N914. This further improves the gain stability of the APD. The dual temperature compensation circuit improves the stability of the APD gain, expands the range of APD's ambient temperature and reduces the thermal noise.