What is a bipolar transistor, its structure, classification, and basic principles 2

Basic principles of BJT

The basic principle of BJT is current control. In PNP transistors, when the collector is at a positive voltage, the base is at a negative voltage, and the emitter is at a negative voltage, the PNP transistor is in an off state and no current flows through; When the collector is at a positive voltage, the base is at a negative voltage, and the emitter is at a positive voltage, the PNP transistor is in an amplified state with current passing through.

In an NPN transistors, when the collector is at a negative voltage, the base is at a positive voltage, and the emitter is at a positive voltage, the NPN transistor is in an off state and no current flows through; When the collector is at a positive voltage, the base is at a positive voltage, and the emitter is at a negative voltage, the NPN transistor is in an amplified state with current passing through.

Key technical points of BJT

The technical key points of BJT include current amplification factor, input resistance, output resistance, maximum withstand voltage, maximum withstand current, and maximum operating temperature.transistors

The current amplification factor refers to the ratio of input current to output current, usually represented by β. The input resistance refers to the ratio of the change in input voltage to the change in input current, usually expressed as ρ. Output resistance refers to the ratio of the change in output voltage to the change in output current, usually represented by r.

The maximum withstand voltage refers to the maximum reverse voltage or maximum forward voltage that a BJT can withstand, usually represented by VCEO and VCBO. The maximum withstand current refers to the maximum current that a BJT can withstand, usually expressed as ICmax. The maximum operating temperature refers to the highest temperature at which BJT can operate normally, usually expressed as Tjmax.transistors