The Function of Capacitor(III)

1) coupling.

For example, the emitter of the transistor amplifier has a self-contained bias resistor, which at the same time makes the signal produce voltage drop back to the input and output signal coupling, which is the coupling component. If a capacitor is connected at the two ends of the resistance, the capacitance is called decoupling capacitance because of the small impedance of the capacitor to the AC signal, which reduces the coupling effect of the resistance.

2) Oscillation / synchronization.

The RC, LC oscillator and the load capacitance of the crystal all belong to this category.

3) time constant.

This is the common R, C series composed of integral circuits. When the input signal voltage is applied to the input terminal, the voltage on the capacitor C) increases gradually. The charging current decreases with the increase of voltage. The characteristics of the current passing through the resistance R) and the capacitance C) are described by the following formula:

I = V / RPU e / CRT)