Characteristics of rectifier diodes

The rectifier diode can use the unidirectional characteristics of the PN junction to turn alternating current into pulsating direct current. It is mainly used for various low-frequency half-wave rectifier circuits, and if it is necessary to achieve full-wave rectification, it needs to be connected to a rectifier bridge.

Characteristics of rectifier diode:

1. Positiveness

When the rectifier diode is applied to the forward voltage, the forward voltage in the beginning of the forward characteristic is very small, can not effectively overcome the blocking effect of the electric field in the PN junction, when the forward current of the rectifier diode is almost zero, this section is called dead zone, and the forward voltage that cannot make the diode on is called dead voltage.

When the forward voltage of the rectifier diode is greater than the dead voltage, the electric field in the PN junction is effectively overcome, the forward conduction of the rectifier diode is on, and the current rises rapidly with the increase of voltage. Over the normal current range, the voltage across the rectifier diode remains virtually constant when on.

2. Reverseness

When the applied reverse voltage of the rectifier diode does not exceed a certain range, the reverse current formed by the small carrier drift movement of the current of the rectifier diode. Since the rectifier diode acts with a small reverse current, the rectifier diode is in the cut-off state. The reverse saturation current of a rectifier diode is affected by temperature.

Generally, the reverse current of silicon rectifier diode is much smaller than that of germanium rectifier diodes, and the reverse saturation current of low-power silicon rectifier diodes is in the order of nA, and the reverse saturation current of low-power germanium rectifier diode is in the order of μA. When the temperature of the rectifier diode increases, the semiconductor is excited by heat, and the number of minority carriers increases.