Definition of MOSFET
MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) is a type of field effect transistor widely used in electronic circuits. It works as a voltage-controlled element and is used for switching or signal amplification purposes.
Basic Features:
It is controlled by voltage (BJTs work with current, while MOSFETs work with voltage).
It has a high input impedance (consumes very little power).
Switching speed is high (often used in digital circuits).
MOSFET is one of the basic building blocks of modern electronics. It works more efficiently and faster than BJTs. N channel and P channel varieties are used in different applications.
What is it used for?
MOSFET Usage Areas:
Power electronics (DC motor drivers, power supplies)
Switching circuits (Fast switching instead of relays) For example, to turn an LED on and off.
Signal amplification (RF circuits, amplifiers. (such as amplifying audio or radio signals)
MOSFET Types
There are two basic types of MOSFETs:
1. N (Negative) Channel MOSFET (NMOS)
Conduction between Drain (D) and Source (S) is achieved when a positive voltage is applied to Gate (G).
It has higher conductivity and fast switching properties.
2. P (Positive) Channel MOSFET (PMOS)
When a negative voltage is applied to Gate (G), Drain (D) and Source (S) become conductive.
It is slower than NMOS, but is used in complementary circuits (CMOS).
N-Channel MOSFETs are more commonly preferred.
Structure Of Mosfet:
Gate (G – Gate): This leg applies the voltage that controls the opening and closing of the MOSFET, that is, the flow of current. You can think of it like the handle of a faucet; when you turn the handle, you control the flow of water.
Drain (D – Drain): The leg where the current comes out of the MOSFET. In other words, the pin to which the load is connected.
Source (S – Source): The leg where the current enters the MOSFET.
The basic operating principle of a MOSFET is to control the current flow between the Drain and Source legs with the voltage applied to the Gate leg. There is no direct electrical connection between the Gate and the Drain and Source; there is a thin layer of insulator (oxide) between them. In this way, the voltage applied to the Gate controls the current between the Drain-Source with a “field effect”
An example circuit for an N-Channel MOSFET;
When a voltage between 4-12 volts is applied to the gate leg of the MOSFET, the lamp lights up. When 0 volts are applied, the lamp turns off.
An example circuit for a P-Channel MOSFET;
When a voltage between 0-5 volts is applied to the gate leg of the MOSFET, the lamp lights up. When 10-12 volts are applied, the lamp turns off.
