The Si avalanche photodetector module integrates a low-noise APD, a low-noise broadband transimpedance amplifier, an ultra-low-noise isolated power supply, a high-voltage supply, and APD temperature compensation. The isolated power supply ensures that the output signal is not affected by external power sources, while the APD temperature compensation enhances the stability of the detector module. The avalanche photodetector features high gain, high sensitivity, wide bandwidth, and low noise.