Conduction conditions and working principle of n-channel MOSFETs

Conduction conditions and working principle of n-channel MOSFETs

Conduction conditions of channel MOS transistor

The conduction and cut-off of Field-effect transistor are controlled by the gate source voltage. For the enhancement of Field-effect transistor, the N-channel mosfet is turned on by adding a forward voltage, and the P-channel  mosfet is turned on by adding a reverse voltage. Generally, 2V to 4V is sufficient.

However, Field-effect transistor can be divided into enhanced type and depletion type. The enhanced type  mosfet can only be turned on by applying voltage, while the depletion type mosfet is already in the conduction state, and the grid source voltage is added to cut it off.

There are only two conditions for switch on and off, and three conditions for triode and Field-effect transistor operation: 1. off, 2. linear expansion, 3. full (base current is continuously added but collector current is no longer added). The circuit that makes the transistor only operate in 1 and 3 conditions is called switching circuit. Generally, the transistor is cut off and the collector does not absorb current to indicate the switch; When the transistor is full and the voltage difference between the emitter and collector is close to 0V, it indicates on. When switching circuits are used in digital circuits, when the output potential is close to 0V, it indicates 0, and when the output potential is close to the power supply voltage, it indicates 1. So the transistors inside digital integrated circuits are all working in a switching state.

Field-effect transistor can be divided into N channel and P channel according to channel

According to information, it can be divided into junction type  mosfet and insulated gate type  mosfet. Insulated gate type tubes are also divided into depletion type and enhanced type. Generally, insulated gate type tubes, abbreviated as MOS diode, are mostly used on motherboards, and enhanced N-channels are mostly used, followed by enhanced P-channels. Junction type  mosfet and depletion type  mosfet are simply unnecessary.

The field effect transistor is called Field-effect transistor for short. It is conductive by most carriers, also called monopole transistor. It belongs to voltage controlled semiconductor devices The Field-effect transistor uses most carriers to conduct electricity, so it is called a unipolar device, while the transistor is called a bipolar device, which uses a few carriers to conduct electricity as well as most carriers The source and drain of some Field-effect transistor can be used interchangeably, and the gate voltage can also be positive or negative, which is more flexible than transistors.