BJT
A BJT, or Bipolar Junction Transistor, is a type of semiconductor device that can amplify or switch electronic signals. It consists of three layers of semiconductor material, which are called the emitter, base, and collector. The operation of a BJT relies on the movement of charge carriers, specifically electrons and holes, allowing it to control current flow.
BJTs come in two main types: NPN and PNP. In an NPN transistor, the current flows from the collector to the emitter, while in a PNP transistor, it flows in the opposite direction. These devices are widely used in various electronic circuits, including amplifiers and digital switches.