Bipolar Junction Transistor (BJT)

A Bipolar Junction Transistor (BJT) is a semiconductor device used to amplify or switch electronic signals. It has three layers of material called the emitter, base, and collector, which are doped with impurities to create two types: NPN and PNP. The BJT works by controlling a larger current flowing between the collector and emitter using a smaller current at the base. This function makes it essential in various applications, from amplifying sound in audio devices to switching circuits in computers, serving as a fundamental building block in modern electronics.