一种用于抑制共模信号的差分放大电路的研究

Research on differential amplification circuit to restrain common-mode signal

在GIS检测系统中,电荷放大器检测到的信号中往往含有较多的共模干扰,常用的电荷放大器满足不了要求。基于此问题,利用电荷放大器的基本原理,设计一种三运放差分放大电路。该电路由3个电荷运算放大器组成,电路中确定了运算放大器的型号以及主要器件和参数。经过Multisim仿真和硬件电路实验检测证明,该电路能有效地抑制GIS闪络故障中的共模噪声,而且拥有较宽的工作频率。因此,该电路可以稳定的工作在频率为10~180 k Hz的范围内,而且能有效地抑制信号中的共模信号干扰,具有失真小、动态范围大等特点。

In GIS detection system,since the signal detected by charge amplifier often contains some common-mode inter-ference,the common charge amplifier can＇t meet the requirement. Based on this problem,a three-operational-amplifying dif-ferential amplification circuit was designed according to the fundamental of the charge amplifier. The circuit consists of three charge amplifiers,in which the type,the main devices and parameters of the operational amplifier are determined. The circuit can restrain common-mode noise in GIS flashover fault effectively and has wide operating frequency,which is verified by Multi-sim simulation and testing of the hardware circuit. This circuit can work at the range of 10~180 kHz stably,restrain the common-mode signal interference in signal effectively,and has the characteristics of low distortion and wide dynamic range.