Transistor - electronic semiconductor device for amplifying, generating and converting electrical signals. Tranzistor allows you to adjust the strength of the electric current. Two main functions of the device in an electric circuit - a switch and an amplifier.
Transistor strengthens weak energy supplied to it by the energy of the signal power source.
In transistor three conclusions: the collector, base and emitter.
Between the collector and emitter current, it is called the collector current, between the base and emitter - weak control current base. The magnitude of the collector current depends on the magnitude of the base current. Moreover, the collector current of the base current is always greater than a certain number of times. This value is called the current gain. Different types of transistors , this value varies from a few to hundreds of times.
Transistors is divided into two major groups:
bipolar transistors (BT) (international term - BJT, Bipolar Junction Transistor);
unipolar transistors, yet they are called field (international term - FET, Field Effect Transistor).
FET works as follows: a weak signal on the gate control a powerful flow through the channel. Unlike bipolar transistors, there is no control of current and voltage.
In FET has a semiconductor channel, which serves as a one capacitor plate and the second plate - a metal electrode disposed through a thin layer of silicon oxide, which is an insulator. When the gate voltage is applied, then the capacitor is charged, and the electric field pulls the gate to the channel charges, resulting in the channel the mobile charges arise capable of forming an electrical resistance and current drain - source sharply drops.
The advantage of FET , compared with bipolar obvious - to be supplied to the gate voltage, but since there is an insulator, the current is zero, and hence the required power to control this transistor will be miserable.
Field (MOS) transistors are P- and N-channel. The principle they have one and the same, the only difference in the polarity of the charge carriers in the channel. Accordingly, in a different direction, and control voltage switching in the circuit.
Field-effect transistors are mostly used in digital technology.
The company has GreenChip offers you preobresti various FETs .