AC Coupling and DC Restoration

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AC coupling (AC COUPLED) is achieved by connecting capacitors in series in the circuit. The type of capacitor is not limited. The function of AC coupling is to remove the DC component in the signal. It has no special effect on pure AC signals (without any DC component). For DC signals, the DC component is removed. This is the characteristic of the capacitor after charging and stabilization. After AC coupling, the known DC component must be restored, which requires clamping (CLAMP) and DC restoration (DC RESTORATION). Regarding clamping, it means superimposing a DC level base point on the AC within a certain range, such as video signals, so that the amplitude range of the AC jumps from one range to another, such as 1-2V to 4-5V, so that it meets the conditions of input and output requirements. The commonly used clamping method is BAV99, or two diodes are connected to the voltage and ground respectively. As shown below: 356338 The BAV99 connection is as above, which actually stabilizes the voltage on the signal line between -0.7V and 5.7V.