Noise analysis and determination method of optimum multiplication rate for APD sensor

Signal to noise ratio (SNR) is an important indicator to measure the performance of high-gain optical sensor. The article first introduced the operating principle of APD sensor. Then three kinds of noise are analyzed in detail. Determination method of optimum gain and computing method of noise equivalent power (NEP) under the condition are proposed basing on the discussion and analysis of APD sensor´s SNR and NEP. According to the conclusion, it is quite convenient to determine the optimum avalanche multiplication of APD sensor and the corresponding NEP levels. It has great theoretical significance and use value for determining and controlling APD sensor´s characteristic of photoelectric transforming and so as to the design of lownoise interface circuit.