A transistor is a semiconductor device, commonly used as an amplifier or an electrically controlled switch. The transistor is the fundamental building block of the circuitry that governs the operation of computers, cellular phones, and all other modern electronics.
Modern transistors are divided into two main categories: bipolar junction transistors (BJTs) and field effect transistors (FETs). Application of current in BJTs and voltage in FETs between the input and common terminals increases the conductivity between the common and output terminals, thereby controlling current flow between them. The transistor characteristics depend on their type. See Transistor models.
The term "transistor" originally referred to the point contact type, but these only saw very limited commercial application, being replaced by the much more practical bipolar junction types in the early 1950s. Today's most widely used schematic symbol, like the term "transistor", originally referred to these long-obsolete devices. For a short time in the early 1960s, some manufacturers and publishers of electronics magazines started to replace these with symbols that more accurately depicted the different construction of the bipolar transistor, but this idea was soon abandoned.
- Bipolar junction transistor
- Field-effect transistor
- Heterojunction Bipolar Transistor
- Tetrode transistor
- Pentode transistor
- Surface barrier transistor
- Micro alloy transistor
- Micro alloy diffused transistor
- Drift-field transistor
- Unijunction transistors
- Darlington transistors
- Insulated gate bipolar transistors (IGBTs)