What is a transistor, its parameter specifications and structural principles 2

3、 Classification of Transistors

According to the different structures and characteristics of transistors, they can be divided into the following categories:

NPN type transistor

NPN transistors is a type of PNP transistor with two P-type outer regions and one N-type middle region. In an NPN transistor, the base is P-type, the emitter is N-type, and the collector is P-type. When a forward voltage is applied between the base and emitter, a small number of carriers in the emitter region are injected into the base region, and these carriers are absorbed by a large number of carriers in the base region, thereby forming current amplification. Therefore, NPN type transistors are mainly used to amplify current or control current.

PNP type transistor

PNPtransistors is a type of PNP transistor with two N-type outer regions and one P-type middle region. In PNP transistors, the base is N-type, the emitter is P-type, and the collector is N-type. When a negative voltage is applied between the base and emitter, a few carriers in the emitter region are injected into the base region, and these carriers are absorbed by a large number of carriers in the base region, thereby forming current amplification. Therefore, PNP type transistors are mainly used for amplifying current or controlling current.

MOSFET

MOSFET is a metal oxide semiconductor field-effecttransistors. MOSFETs typically consist of three regions, namely the source region, the drain region, and the gate region. The gate region is generally a combination of a metal layer and an oxide layer. When a voltage is applied to the gate, electrons in the gate region form a channel between the source and drain regions, thereby forming a leakage current. The main characteristics of MOSFETs are high input impedance, low power consumption, fast speed, and low noise, so they are widely used in electronic devices.

4、 Summary

A transistors is a common electronic component whose main function is to amplify or control current. A transistors consists of three regions, namely the emitter region, the base region, and the collector region. The parameter indicators of a transistor include gain, maximum dissipated power, maximum voltage, maximum current, etc. According to their different structures and characteristics, transistors can be divided into NPN type transistors, PNP type transistors, and MOSFETs. In practical applications, the appropriate transistors model should be selected according to the needs to achieve the best circuit effect.