Four common methods for analyzing circuits (II)

3. DC equivalent circuit analysis method

When analyzing the circuit principle, it is necessary to understand the DC path and the AC path in the circuit. The DC path refers to the static bias of each semiconductor transistor and integrated circuit when there is no input signal, that is, their static operating point. The AC circuit refers to the way of AC signal transmission, that is, the ins and outs of the AC signal.

In an actual circuit, an AC circuit and a DC circuit coexist in the same circuit, and they are connected to each other and different from each other.

The DC equivalent analysis method is a method for separately analyzing the DC system of the circuit being analyzed. When performing the DC equivalent analysis, the processing function of the input AC signal is not considered at all, and only the direct current voltage of the power supply is considered. The resulting quiescent DC current, voltage, and the relationship between them.

For DC equivalent analysis, the DC equivalent circuit diagram should be drawn first. The following principles should be followed when drawing the DC equivalent circuit diagram: the capacitors are always treated as open circuits, and the inductors that can ignore the DC resistance should be regarded as short circuits. The inductors that cannot ignore the resistance components can be equivalent to resistors. Take the voltage after the buck decoupling as the supply voltage of the equivalent circuit; consider the semiconductor diode in the reverse bias state as an open circuit.

4, AC equivalent circuit analysis method

The AC equivalent circuit analysis method is a method of separating the AC system in the circuit from the circuit and performing separate analysis.

When AC equivalent analysis, the AC equivalent circuit diagram should be drawn first. To draw the AC equivalent circuit diagram, the following principles should be followed: the power supply is regarded as a short circuit, and the AC bypass capacitor is always short-circuited, and the DC-coupler is always regarded as a short circuit.