A transistor is a miniature semiconductor device that regulates or controls current or voltage flow, amplifies and generates electrical signals, and acts as a switch. It is one of the basic building blocks of modern electronics. A transistor is composed of semiconductor material, usually with at least three terminals. The three terminals are:
- Emitter: The emitter is the transistors negative lead.
- Base: The base is the terminal that activates the transistor.
- Collector: The collector is the terminal that collects the current.
A transistor can use a small signal applied between one pair of its terminals to control a much larger signal at another pair of terminals, a property called gain. It can produce a stronger output signal, a voltage or current, proportional to a weaker input signal, acting as an amplifier. It can also be used as an electrically controlled switch, where the amount of current is determined by other circuit elements. There are two types of transistors, with slight differences in how they are used:
- BJT (Bipolar Junction Transistor): BJT is a type of transistor that uses both electrons and holes as charge carriers.
- FET (Field Effect Transistor): FET is a type of transistor that uses an electric field to control the shape and hence the conductivity of a channel of one type of charge carrier in a semiconductor material.
Transistors are commonly used in digital circuits as electronic switches which can be either in an on or off state, both for high-power applications such as switched-mode power supplies and for low-power applications such as logic gates. They are versatile devices that can act as switches, amplifiers, and signal regulators, thereby enabling the processing and storage of digital information. The widespread use of transistors in electronic devices has greatly impacted our daily lives by enabling modern communication, entertainment, transportation, and healthcare technologies.
