MOSFET: How it works Its Symbol and Deplition vs Enhancement Mode

MOSFET is a metal oxide semiconductor transistor which belongs to FET (field-effect transistor) class of transistors. In this post, you’ll learn the working of MOSFET, its symbols and depletion vs enhancement mode.


A MOSFET is three terminal device. The terminals are namely the:
  1. Gate
  2. Drain
  3. Source

Both symbols of n-channel and p-channel MOSFET along with a practical model (TO-220) is represented along with labels. Using this symbol you can identify the gate, drain, and source on the device.


Working Modes: Depletion mode vs Enhancement mode

In depletion mode, MOSFET works like a switch. Whereas in enhancement mode it works like a variable resistor. The video below explains the working of MOSFET.

A point to remember

The MOSFET is often used in high current applications, you should use a heat sink if your circuit dissipates a lot of power. You can use the Ohm’s law calculations for this purpose (as explained in the video).


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