在某些测量系统中,常常需要将一个与较大的直流漂移电压即频率甚低的起始成分联系在一起的低电平、低频率的信号放大。要使被放大的信号在放大或记录级的动态范围之内是很重要的。当用图表式记录器的高灵敏档记录这种信号时,问题就很明显了。每当直流漂移电压稍有变化时,则输出就饱和。放大器输入可用一简单高通滤波器,以消除直流漂移来防止饱和。可是,这种方法带来的实际困难是有相位失真及瞬态恢复时间长。当该信号含有甚低频时,则简单滤波 In some measurement systems, it is often necessary to amplify a low-level, low-frequency signal associated with a large DC offset voltage, a very low-frequency start-up component. It is important that the amplified signal be amplified or recorded within the dynamic range of the stage. The problem is obvious when recording this signal in a highly sensitive file with a chart recorder. The output is saturated whenever the dc drift voltage changes slightly. A simple high-pass filter is available at the amplifier input to eliminate dc drift and prevent saturation. However, the practical difficulty with this approach is the phase distortion and transient recovery time. When the signal contains very low frequency, then the simple filter