The switching time of the switching diode is mainly determined by the transition time from the on state to the off state, which is also called the reverse recovery time. The time required from the beginning of the reverse bias until the reverse current drops to 1/10 of the initial value is called the reverse recovery time. When the P+N switching diode is in on-state, the holes are injected from the P+ region to the N region to form a forward conduction current, that is, there is always a small number of carriers stored in the N region. After the reverse bias is added, the diode can only be in the off state if the few carriers stored in the N-region are completely excluded.
Working principle
When the semiconductor diode is on, it is equivalent to the switch is closed (the circuit is on), and when the switch is off, it is equivalent to the switch is open (the circuit is off), so the diode can be used as a switch, and the common model is 1N4148. Because the semiconductor diode has the characteristics of unidirectional conduction, the PN junction is switched on at positive bias voltage, and the resistance in the on-state is very small, about tens to hundreds of euros; Under reverse bias, it is a cutoff state, and its resistance is very large, generally silicon diodes are more than 10ΜΩ, and germanium tubes also have tens to hundreds of thousands of euros. Using this characteristic, the diode will play a role in controlling the current in the circuit to turn on or off, becoming an ideal electronic switch.
