针对恒虚警下雪崩光电二极管输出信号、噪声与倍增因子相互影响的问题, 分析了雪崩光电二极管自身噪声、背景辐射对其探测性能的影响及恒虚警补偿方式的原理, 建立了背景辐射与恒虚警下倍增因子的关系模型.对模型进行了实验验证, 并通过仿真分析了不同虚警概率、阈值电流、噪声电流下背景辐射与倍增因子的关系.结果表明：倍增因子会随背景辐射的增大而减小, 且减小速率逐渐减缓; 当背景辐射不变时, 虚警概率或阈值电流的增大都会使倍增因子增大; 热噪声与放大器噪声有效值之和对倍增因子影响较大, 而暗电流对倍增因子的影响较小.

Aiming at the mutual influence of signal, noise and multiplication factors of the avalanche photodiode under constant false alarm, the effects of the avalanche photodiode′s own noise and background radiation on the detection performance and the principle of constant false alarm noise compensation were analyzed. The relationship model of background radiation with the constant false alarm multiplication factor were established. The model was verified by experiments, and the relationship between background radiation and multiplication factors under different false alarm probability, threshold current, and noise current was simulated and analyzed. It is found that the multiplication factor would decrease with the increase of background radiation, and the decreasing rate gradually slows down. When the background radiation is constant, the increase of the false alarm probability or the threshold current will increase the multiplication factor. The sum of effective value of the thermal noise and the amplifier noise has a greater influence on the multiplication factor, while the dark current has less influence on the multiplication factor.