电荷灵敏前置放大器消除电源噪声的设计

Power supply denoising design for charge-sensitive preamplifier

在高灵敏度光电探测领域,常常采用雪崩二极管(APD)等高增益探测器,这些探测器通常需要上百伏的工作电压,因此电源噪声对探测器的性能影响很大。针对单光子探测的需要,论文提出了一种电荷灵敏前置放大器消除电源噪声的设计,通过采用匹配的差分输入,可以有效抵消电源的共模噪声。论文首先对APD探测器在不同偏压下的结电容进行测试,然后采用可调电容对APD电容进行匹配,用MultiSim对提出的电路进行了仿真分析,最后制作实验电路进行了测试和验证。结果表明:差分输入电荷灵敏前置放大器能够有效消除电源噪声(包括低频噪声和高频噪声),实现高灵敏度的光探测。

High gain photon detectors such as avalanche photo diode （APD）are widely used for high-sensitivity photon detection. However, the high voltage applied to these detectors often makes serious noise. In order to perform high-sen- sitive photon detection, an innovative denoising design for charge-sensitive preamplifier is proposed,which can reduce the power-supply noise by differential amplification. Firstly, the junction capacitance of APD is tested under various bias voltages. Then capacitance matching is made with an adjustable capacitor and circuit simulation is performed with Multisim software. Finally the fabricated circuit is tested. It is shown that the charge-sensitive pre-amplifier with differ- ential input can significantly reduce the power-supply noise（ both low frequency and high frequency）and realize high sensitivity.