What is Transistor and types of transistors?

A transistor is a semiconductor device that amplifies or switches electrical signals and power. The transistor is one of the basic building blocks of modern electronics and It is composed of semiconductor material, usually with at least three terminals for connection to a circuit. A voltage or current applied to one pair of the transistor’s terminals controls the current through another pair, because the controlled output power can be higher than the controlling input power, a transistor can amplify a signal. Some transistors are packaged individually, but many more are embedded in integrated circuits.

Types of transistors

  • Bipolar Junction Transistor
  • Field Effect Transistor

Bipolar Junction Transistor

A Bipolar junction transistor actually termed BJT is called so as it has two PN junctions for its function. The BJT is nothing but a normal transistor and It has two types of configurations NPN and PNP. Usually, an NPN transistor is preferred for the sake of convenience and BJT is a current-controlled device. The types of BJT are NPN and PNP transistors. The NPN transistor is made by placing a p-type material between two n-type materials. The PNP transistor is made by placing an n-type material between two p-type materials.

Field Effect Transistor

A FET is a three-terminal unipolar semiconductor device. It is a voltage-controlled device, unlike a bipolar junction transistor. The main advantage of FET is that it has a very high input impedance, which is in the order of Mega Ohms. It has many advantages like low power consumption, and low heat dissipation, and FETs are highly efficient devices. The Brief discussion about Bipolar and FET transistors in the next article.

Transistor Characteristics

  • Input Characteristics: These describe the changes in input current with the variation in the values of input voltage keeping the output voltage constant.
  • Output Characteristics: This is a plot of output current versus output voltage with the constant input current.
  • Current Transfer Characteristics: This characteristic curve shows the variation of output current in accordance with the input current, keeping the output voltage constant.

Unit of Transistor

The units of a transistor for electrical measurement are Ampere (A), Volt (V), and Ohm (Ω), respectively, because the word transistor is a combination of transfer and resistance.

Application of Transistor

  • Computer Memory chips
  • Electronic Games
  • Cameras
  • MP3 player
  • Microprocessors

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