The role of coupled circuit
The function of capacitive coupling is to pass the AC signal from the previous stage to the next stage. The coupling method is also a direct coupling and a transformer coupling method. The direct coupling efficiency is the highest, and the signal is not distorted. However, the adjustment of the front and rear working points is complicated and involved. In order to make the working point of the latter stage not affected by the previous level, it is necessary to separate the former stage and the latter stage in terms of DC, and at the same time, the AC signal can be smoothly transmitted from the previous stage to the latter stage, and at the same time, The way to accomplish this task is to use capacitive transmission or transformer transmission. They can transmit AC signals and block DC, so that the working points of the front and rear stages are not involved. But the difference is that when transmitting with a capacitor, the phase of the signal is delayed. When transmitting with a transformer, the high-frequency component of the signal is lost. Under normal circumstances, when a small signal is transmitted, a commonly used capacitor is used as a coupling element. When a large signal or a strong signal is transmitted, a common transformer is used as a coupling element.