用于DVS系统的平衡探测器的设计

Design of balanced detector for DVS system

在DVS系统中,为了克服由于耦合器分束比的不平衡和PIN管的不一致,导致平衡探测器输出信号呈现非线性甚至饱和的问题。本文分析了平衡探测器的工作原理,并设计、研制了一种带有带通滤波器的平衡探测器。通过带通滤波器对TIA输出的直流和带外噪声进行抑制,避免后级放大器输出饱和,提高探测器对交流信号的放大能力,提高系统的信噪比。实验结果表明,探测器的跨阻增益为60 kV/A,探测器输出噪声幅度为27 mV,80 MHz处信噪比为30 dB,该平衡探测器具有抵抗输入光不平衡的能力,能长时间稳定运行,满足DVS系统对光信号检测的要求。

In the DVS system,in order to overcome the problem that the balanced detector output signal shows nonlinearity or even saturation,which is cased by the imbalance of the coupler split ratio and the inconsistency of the PIN tube.This paper analyzes the working principle of the balanced detector,and a balanced detector with a bandpass filter is designed and studied.The DC component and the out-of-band noise of the TIA output are suppressed by the band-pass filter to avoid saturation of the output of the postamplifier,improve the amplification capability of the detector for the AC signal,and improve the signalto-noise ratio of the system.The experimental results show that the detector’s transimpedance gain is60 KV/A,The noise amplitude of detector is 27 mV,and the signal-to-noise ratio is 30 dB at 80 MHz.The balance detector has the ability to resist unbalanced input light and can operate stably for a long time,which meet the requirements of the DVS system for optical signal detection.