通过分析基于L-C耦合跨阻运放电路的散粒噪声探测器噪声来源, 提出了电感的寄生电容对电子学噪声影响的分析模型, 并进行了实验验证.研究表明, 电感的寄生电容会增大跨阻运放的输入电压噪声增益, 从而增加探测器的电子学噪声.当总电感值为1 mH时, 选用两个0.5 mH的电感串联结构相比选用单个1 mH的电感, 探测器电子学噪声明显降低.由于电感的自共振频率越低, 寄生电容越大, 选用高自共振频率的电感有助于进一步降低电子学噪声.实验测量得到, 在2.5 MHz分析频率处, 选用两个0.5 mH、自共振频率为6 MHz的电感串联相比选用单个1 mH、自共振频率为1.6 MHz的电感, 电子学噪声的降低了3 dB.在相同入射激光条件下, 该改进模型可以有效提高探测器的信噪比.

By analyzing the electronic noise sources of shot noise photodetector based on the L-C coupled transimpedance amplifier circuit, the effect of the parasitic capacitance of the utilized inductance on the electronic noise was theoretically investigated and experimentally validated. The result shows that the parasitic capacitance of the inductor may increase the electronic noise of the detector via increasing the input voltage noise gain of the transimpedance amplifier. Given that the total inductance of the L-C circuit is 1 mH, the contribution to the electronic noise of choosing two series inductor with 0.5 mH each is much smaller than that of choosing a single inductor with 1mH. Furthermore, the higher the self resonant frequency of the inductor is, the smaller the parasitic capacitance and thus the smaller the electronic noise will be. The experiment results show that, at the analyzing frequency of 2.5 MHz, the electronic noise reduction of the two inductors in series with inductance of two 0.5 mH and resonance frequency of 6 MHz can reach up to 3 dB, compared to that using a single 1 mH inductor with the resonance frequency of 1.6 MHz. Under a certain incident optical power, the signal-to-noise ratio of the detector can be thus improved effectively.