What is the principle of operation of MOSFET?

MOSFET (FieldEffect Transistor abbreviation (FET)) title MOSFET. by a small number of carriers to participate in the thermal conductivity, also known as multi-pole junction transistor. It is categorized as a voltage-controlled semi-superconductor device. Existing output resistance is high (10 ^ 8 ~ 10 ^ 9 Ω), low noise, low power consumption, static range, easy to integrate, no second breakdown phenomenon, the insurance task of the wide sea and other advantages, has now changed the bipolar junction transistor and power junction transistor of the strong collaborators.

MOSFET characteristics

First: MOSFET is a voltage mastering device, it through the VGS (gate source voltage) to master ID (drain DC);

Second: MOSFET's output DC is very small, so its output resistance is very large.

Three: it is applied a few carriers to conduct heat, and thus it has a better measure of stability;

Four: it consists of a reduced path of electrical reduction of small coefficients to be smaller than the transistor consists of a reduced path of electrical reduction of small coefficients;

Fifth: MOSFET anti-irradiation power;

Six: because there is no faulty activity of the minority dispersion caused by scattered particles of noise, because the noise is low.

MOSFET task principle

MOSFET task principle in one sentence, that is, "drain - source walk through the channel between the ID, with the electrode and the channel between the pn constructed into a reverse bias electrode voltage to master the ID". More accurately, the amplitude of ID across the circuit, that is, the channel cross-sectional area, it is by the pn junction counter-biased variation, the occurrence of the depletion layer to expand the variation of the mastery of the reason. In the non-saturated sea of VGS=0, the expansion of the indicated transition layer is not very large because, according to the magnetic field of VDS added between the drain-source, some electrons in the source sea are pulled away by the drain, i.e., there is a DC ID activity from the drain to the source. The moderate layer expanding from the gate to the drain will form a blockage type of a whole body of the channel, ID full. Refer to this pattern as pinch-off. This symbolizes that the transition layer obstructs a whole of the channel, and it is not that the DC is cut off.

In the transition layer, because there is no self-movement of electrons and holes, in the real form of the insulating characteristics of the existence of the general DC current is difficult to move. However, the magnetic field between the drain - source, in practice, the two transition layer contact drain and gate pole lower left, because the drift magnetic field pulls the high-speed electrons through the transition layer. Because the strength of the drift magnetic field simply does not change the fullness of the ID scene. Secondly, VGS to the negative position change, so that VGS = VGS (off), then the transition layer largely change the shape of covering the entire sea. And the magnetic field of VDS is largely added to the transition layer, the magnetic field that pulls the electron to the drift position, as long as close to the source pole of the very short all, which is more so that the DC power is not able to stagnate.