如何抑制直接耦合放大电路中零点漂移

Suppression Method of Zero-drift in Direct-coupled Amplifying Circuit

直接耦合放大电路既能放大交流信号,又能放大缓变信号和直流信号,其频率特性的下限频率为零。在集成电路中,由于容量较大的电容器难以制作,因此集成放大电路一般采用直接耦合的结构。但是,直接耦合方式又给放大电路带来一个特殊的问题,这个特殊的问题就是零点漂移,在此介绍直接耦合放大电路的特点和直接耦合带来的特殊问题,根据产生这个问题的原因,讲述解决抑制零点漂移的各种措施。着重讲述利用差动放大电路抑制零点漂移的工作原理。

The direct-coupled amplifier circuit, whose lower limit frequency of the frequency characteristics is zero, can amplify the AC signals, slowly varying signals and DC signals. The direct coupling structure is generally adopted in the integrated amplifying circuit since the large-capacity capacitors in the integrated circiuts are difficult to make. However, the direct coupling amplifying mode brings about a particular issue, which is called ＂zero drift＂. The characteristics of the direct-coupled amplifying circuits and the special problems caused by the direct coupling are described. A variety of measures to solve the problem of the zero drift and the productive reason of the problem are elaborated. The principle to suppress the zero drift with the differential amplifying circuit is described emphatically.