The Wide Field of View Cherenkov Telescope Array (WFCTA) of Large High Altitude Air Shower Observatory (LHAASO) uses silicon photomultiplier tube (SiPM), a new solid state semiconductor detector, as a photosensitive detector. Since the gain of SiPM is sensitive to temperature, in order to keep the gain of SiPM stable under the environment of variable temperature, a precise compensation method for SiPM gain temperature drift is developed in this paper. The method realizes the bias adjustment of LDO output by means of coarse and fine adjustment of two digital potentiometers. According to the relationship between the calibrated ADC monitoring value and the real bias voltage, we uses the ADC monitoring value for feedback regulation to realize the precise bias adjustment, and finally obtain the accurate compensation of SiPM gain. Using the circuit realized by this method, the gain fluctuation of SiPM is reduced from 71.8% before compensation to 0.8% within the similar temperature variation range. The results show that this method can achieve a good compensation effect for SiPM gain temperature drift.
