In this lesson we will learn what is is transistor Working of transistor and other detail. A transistor is a fundamental electronic component of electronic devices or circuits. A transistor is used to amplify and switch electronic signals to control the flow of electric current in electrical or electronic circuits. It is a three-layer semiconductor device that can be either made of germanium, silicon, or other semiconductor materials. There are many types of transistors but the most common types is bipolar junction transistors (BJTs) and field-effect transistors (FETs).
Terminals of Transistor
A transistor consists of three terminals and each terminal has a specific function. The names and functions of terminals depend on the type of transistor. There are two main types of transistors BJT and FET.
For Bipolar Junction Transistors (BJT) the name of terminals are:
For Field-Effect Transistor (FET) the names of terminals of transistor are:
- Gate (G):
- Source (S):
- Drain (D):
Three terminals of a transistor
Almost all transistors consists of three terminals (Emitter, Base and Collector) the functions of these terminals may differ in differ types. The basic function of these terminals are given below.
- Emitter (E): The primary function of the emitter in a Bipolar Junction Transistors is to emit or release charge carriers (electrons for NPN and holes for PNP) into the base region when a small current is applied to the base terminal of transistor.
- Base (B): The base of transistors plays a critical role to control the flow of current between the emitter and collector. It is a key terminal of any transistor in the operation. The function of the base varies between NPN and PNP transistors.
- Collector (C): The collector terminal of transistor is used to collect the charge carriers that flow from the emitter when the transistor is in an active state.
How transistor works
The basic transistor working is to control the flow of current from emitter to collector. As we discussed that there are two types of transistor BJT and FET. Further BJT and FET also has two types (NPN and PNP):
Working of NPN BJT transistor:
- The transistor consists of three terminal or pins: emitter, base , and collector.
- When a small current flows from the base to the emitter then it allows a large current to flow from the collector to the emitter.
- The flow of electrons from the emitter to the collector is controlled by the number of electrons injected from the emitter to the base so the base is used to control the flow of current from emitter to collector.
- NPN transistor control Negative current and on base terminal positive current is applied in very small value.
- In NPN transistors Positive current is applied on base to control the flow of current and in PNP transistors Negative current is applied in the base of transistor to control the flow of current from emitter to collector
Field-Effect Transistor Working:
In N-channel MOSFET transistor working is given below:
- The MOSFET N-channel transistor has three terminals: gate, source, and drain.
- When a positive voltage is applied to the gate, it creates an electric field current flows from source to the drain in much large amount. So the current is control through Gate current.
- FET transistors are commonly used for switching or amplifying in electronic circuits, especially in digital logic circuits.
- In P-channels FET small negative current is applied to control the flow of current from source to drain.
Importance of Transistor
The main transistor purpose is to control flow of current in the electronic or electrical device to use these devices according to uses. Without Transistor it is impossible to control follow of current as we want.