Bipolar Junction Transistors

Abstract

The bipolar junction transistor is a three-terminal ‘active’ device that may be used to control the flow of current through a load resistor from an external power source (such as a power supply) by means of a small power signal applied to its control terminal. It may thus be used as a power amplifier. The bipolar junction transistor (BJT) is so called because both polarities of current carrier are involved in the transport of current. It is normally referred to simply as a transistor. The transistor may be used in a wide variety of electronic circuit applications, such as amplifiers, switches, oscillators, filters, power supplies and many more.