In the world of electronics, transistors are considered an essential component. A transistor is a semiconductor device that is used for amplifying the signals and in switching circuits. A basic model of a transistor comes with three terminals, which are emitter (E), base (B), and collector (C). There are advanced transistors that come with a fourth terminal known as substrate (S). A transistor is an active device.
Classification of Transistor
A transistor can be divided into two major subdivisions and this division consists of bipolar junction transistor (BJT) and field-effect transistor (FET).
Further BJTcan be divided as NPN and PNP transistors. While FET can be divided as JFET and MOSFET.
A transistor in which one p-type material is sandwiched between two n-type materials is known as NPN transistor which is a type of BJT. The main use of NPN transistors is to amplify the weak signals that are entering through the base, thus producing strong amplified signals at the collector. The electrons move from emitter to collector region. This movement of electrons makes NPN transistor the most desirable transistor in the circuit as the majority of charge carriers are electrons.
A transistor in which two p-type materials are sandwiching one n-type material is known as a PNP transistor which is a type of BJT. This type of transistor can be called a current controlled device. A small amount of current in the base controls the current in the emitter and collector. The majority of charge carriers in the PNP transistor are holes. There are two crystal diodes that are connected back to back in a PNP transistor. The left side of the diode is known as the emitter-base diode while the right side of the diode is known as the collector-base diode.
MOSFET stands for Metal Oxide Field Effect Transistor. It is a type of FET. Unlike BJT, MOSFEThas a gate, drain, and source connection. A MOSFET can be of two types:
- Depletion type MOSFET
- Enhancement type MOSFET
In this device, the conductivity of the device is decided by the voltage. It is commonly used in digital circuits.
JFET stands for Junction gate Field Effect Transistor. It is a type of FET that has a gate, drain, and source connections. JFET is considered to be an essential component since it is used in analogue electronics for precision level voltage. It is also used as a voltage-controlled resistor. The power consumption and power dissipation are low in a JFET.
To learn more about the circuit diagram of the transistor types along with their construction and working, stay tuned with BYJU’S.