Working principle and category of crystal diodes 3

1. Positive characteristics

In electronic circuits, connecting the positive terminal of a diode to the high potential terminal and the negative terminal to the low potential terminal will cause the diode to conduct. This connection method is called forward bias. It must be noted that when the forward voltage applied across the diode is very small, the diode still cannot conduct, and the forward current flowing through the diode is very weak. Only when the forward voltage reaches a certain value (this value is called the "threshold voltage", which is about 0.2V for germanium tubes and about 0.6V for silicon tubes), can the diode conduct directly and positively. After conduction, the voltage across the diode remains basically unchanged (germanium tube is about 0.3V, silicon tube is about 0.7V), which is called the "forward voltage drop" of the diode.

2. Reverse characteristic

In electronic circuits, the positive terminal of a diode is connected to the low potential terminal, and the negative terminal is connected to the high potential terminal. At this time, there is almost no current flowing through the diode, and the diode is in a cut-off state. This connection method is called reverse bias. When a diode is reverse biased, there will still be a weak reverse current flowing through the diode, which is called leakage current. When the reverse voltage across the diode increases to a certain value, the reverse current will sharply increase, and the diode will lose its unidirectional conductivity characteristics. This state is called diode breakdown.