Introduction to diode types

There are many types of diodes, which can be divided into two categories according to their usage: germanium diodes and silicon diodes.

If classified by purpose, it can be divided into ordinary diodes and special diodes. Ordinary diodes include detection diodes, switching diodes, and voltage regulator diodes; Special diodes include varactor diodes, photodiodes, light-emitting diodes, etc. The commonly used diodes in circuits are introduced as follows.

(1) Rectifying diode.

A diode that rectifies alternating current into direct current is called a rectifying diode. Rectifiers are often made of silicon semiconductors, which utilize the unidirectional conductivity of PN junctions to convert alternating current into pulsed direct current, known as rectification.

(2) Detector diode.

The detection diode can detect low-frequency signals modulated on high-frequency electromagnetic waves, and it has high detection efficiency and good high-frequency characteristics.

(3) Zener diode.

Zener diodes use the principle that the voltage at both ends remains constant when the diode is reverse broken down to achieve voltage regulation, limiting, and overload protection. They are widely used in voltage regulation power supply devices.

(4) Switching diode.

Switching diodes utilize the unidirectional conductivity of small resistance in forward bias and large resistance in reverse bias to control the current in the circuit, playing a switching role of connection or disconnection.

(5) Variable capacitance diode.

Variable capacitance diodes utilize the characteristic of PN junction capacitance changing with the magnitude of the reverse voltage applied to the diode, replacing variable capacitance in tuning and other circuits.

(6) Light emitting diode.

When the forward voltage of the light-emitting diode is between 1.5-3V, it can emit light as long as the forward current passes through. Light emitting diodes are mainly used for indication and can form LED digital diodes for numbers or symbols.

(7) Photodiode.

Photodiodes convert photoelectric information into electrical signals, and their reverse current increases proportionally with the intensity of light when illuminated. They are used for measuring light or as an energy source, namely photovoltaic cells.

(8) Fast recovery diode.

Fast recovery diode is a semiconductor diode with good switching characteristics and short reverse recovery time. It is mainly used in electronic circuits such as switching power supplies, PWM pulse width modulators, and frequency converters. It is used as a high-frequency rectifier diode, freewheeling diode, or damping diode.