A transistor is a semiconductor device that switches or amplifies electrical signals — and as a tiny, electrically controlled on/off switch it is the fundamental building block of all modern digital electronics.¹

Overview

A transistor uses a small voltage or current at one terminal to control a much larger current between two others, so it can act as an amplifier or as a switch. Invented at Bell Labs in 1947, it replaced the bulky, hot vacuum tube. The dominant type in digital chips is the MOSFET, billions of which are etched together on a single integrated circuit. Wired together, transistors form the logic gates that implement all computation.

Where it fits

Every digit a computer manipulates ultimately comes down to transistors switching on and off. Their relentless shrinking is what Moore’s law describes and what lets a modern CPU pack billions of switches into a fingernail-sized die. The same devices also do analog work: in an SDR front end, transistors amplify faint RF in a low-noise amplifier before the signal is digitized for GopherTrunk to decode.

Sources

1. Transistor — Wikipedia, on the transistor as switch and amplifier and the basic building block of electronics. ↩

See also

• Semiconductor
• Integrated circuit
• Logic gate
• Moore's law
• Central processing unit (CPU)
• Clock speed