低噪声光电检测电路的设计和噪声估算  

Design of an Optic-Electric Detecting Circuit with Low Noise and Its Noise Calculation

作　　者：王林涛[1] 李开成[2] 张健梅[2] 

机构地区：[1]武汉理工大学信息工程学院,湖北武汉430070 [2]华中科技大学电气与电子工程学院,湖北武汉430074

出　　处：《武汉理工大学学报（信息与管理工程版）》2001年第3期16-18,共3页Journal of Wuhan University of Technology：Information & Management Engineering

基　　金：湖北省自然科学基金资助项目 ( 2 0 0 0J12 8)

摘　　要：论述了低噪声光电检测电路的设计及相关问题 ,指出光电检测电路要求具有较高的信噪比 ,在较宽的频带范围内无频率失真 ,信号具有较大的传输功率 ;低噪声前置放大器的选择应与源阻抗相适应 ,对于内阻约为几十kΩ至上百kΩ的硅光电探测器 ,可采用高性能场效应管作前置放大器 ;考虑到光电二极管具有恒流源特性及内阻大的特点 ,为了获得较大的信号幅度 ,光电转换需要把高阻抗的电流源变成低阻抗的电压源 ,然后再与负载相连。分析了频带与噪声电压的关系 ,计算了光电探测器的噪声电压和噪声电流以及它们在放大器输出端形成的噪声电压 ,并对光电转换的信噪比进行了计算。基于低噪声光电探测电路设计的光纤电压互感器可获得 0 .2 %的电压测量精度 。The design of an optic electric detecting circuit with low noise is described and the relationship between the frequency ban and noise voltage is analyzed. It is pointed out that this circuit requires a high signal to noise ratio, no frequency distortion in a wide frequency range and large transmission powers of signals. A forward amplifier with low noise should match the source impedance. For the optic electric detector with inner impedance from ten kilo Ohmes to a hundred kilo Ohmes, it is suitable to choose a transistor chip with high performance as an amplifier. As the optic electric diode has constant current source characteristic with a high inner impedance, in order to obtain a larger signal amplitude, the high impedance current source should be converted to the low impedance voltage source and then connected to the load through an optic electric converter. The noise voltage, the noise current and their output voltages at the terminal of amplifier are calculated, and the signal to noise ratio of the optic electric conversion circuit is estimated. The optical fiber transformer based on an optic electric conversion with low noise gains voltage measurement accuracy of 0.2%, satisfying the requirements of transient signal measurement.

关 键 词：光电转换 电路设计 噪声计算 光电检测电路 噪声电压 噪声电流 光纤电压互感器 

分 类 号：TN215[电子电信—物理电子学]