Transistor

Introduction:

A transistor is a semiconductor device which is used to amplify the signals as well as in switching circuits. Generally, it consists of three terminals emitter(E), base(B) and collector(C) and two P-N junctions. It is one of the active components.

It was invented by John Bardeen, William Shockley and Walter Brattain in 1948, in Bell Telephone Laboratories.

Transistors are divided into different types depending on their construction and operation.


Transistors are basically classified into two types; they are Bipolar Junction Transistors (BJT) and Field Effect Transistors (FET). The BJTs are again classified into NPN and PNP transistors. The FET transistors are classified into JFET and MOSFET. Junction FET transistors are classified into N-channel JFET and P-channel JFET depending on their function. MOSFET transistors are classified into Depletion mode and Enhancement mode. Again depletion and enhancement mode transistors are classified into N-channel JFET and P-channel.

depending on their function some other transistors are also available.

• Small signal transistors


• Small switching transistors


• Power transistor


• High frequency transistor


• Photo transistor


• Uni junction transistor

comparison of BJT and FET: