Transistors are at the core of modern electronic technology, and they have enabled a lot of everyday devices that we take for granted today. Modern-day computers contain 7th billionths of a metre of transistors and that’s not all. Everything from mobile phones to cars and radios contains transistors.
Each of these technologies contains a specific transistor and they all work in their own unique way. Read this guide to find out about the different types of transistors available and how they work:
What is a transistor?
A transistor is an electric component that lets current flow through it in one direction and can turn current on and off. It can be used to both conduct and insulate electric current or voltage, essentially acting as a switch and amplifier.
A transistor is typically composed of a base, collector, and emitter. The base is used to activate the transistor while the collector is the positive lead, and the emitter is the negative lead.
What are the different types of transistors?
Transistors are generally divided into three types: bipolar junction transistors (BJTs), field-effect transistors (FETs), and insulated-gate bipolar transistors (IGBTs).
BJTs
This type of transistor uses both electrons and holes as charge carriers and includes is split into NPN and PNP. Both are used in varying amplification circuits and modulating circuits, with the most common operation mode being the ON and OFF switch. NPN transistors turn on when the current flows through the base of the transistor from the collector to the emitter.
PNP transistors can be used for sourcing current and turning off an application at a push of a button, like in emergency shutdowns. This is the exact opposite of an NPN transistor as the charge carriers are holes and the materials used to construct its components are different from the NPN. Also, the base-collector terminals of the PNP transistor are reversed-biased.
FETs
FETs are typically used in everything from motor drivers to voltage regulators and specialty amplifiers and they have some added features that make them a better choice than BJTs. FETs are subdivided into three types: insulated FETs (MOSFETs), junction FETs (JFETs), and metal-semiconductor FETs (MESFETs).
MESFETs are often used as drivers or switchers for applications requiring high power outputs, although MOSFETs have the broadest range of practical power electronics applications.
IGBT
This semiconductor has three terminals that are used in complex amplifiers and for fast switching with high efficiency. It is a fusion between a MOSFET and BJT. The collector and the emitter are the conduction terminals, and the gate is the control terminal where the switching operation is controlled.
There are two types of IGBT available: Punch through and Non-punch through. These are differentiated by the absence or presence of the n+ buffer layer.
