Research on the associated feature of APD sensor avalanche gain and photoelectric conversion SNR

The source of APD photodiode sensor working noise and changes of photoelectric conversion SNR (Signal-to-noise ratio) are analyzed and computed in detail. The paper emphatically introduces the associated feature of APD sensor avalanche gain and photoelectric conversion SNR. Then the determination method of optimum avalanche multiplication rate on various noise factors is discussed. It can be seen from the research report that the optimum avalanche multiplication rate tends to reduce while the photocurrent Ip increases. Photoelectric conversion SNR decreases as APD operation bandwidth increases while the optimum avalanche multiplication rate remains unchanged. 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 low-noise interface circuit.