This document discusses the construction and working of MOSFET transistors. It describes the key differences between depletion mode and enhancement mode N-channel MOSFETs and compares their drain and transfer characteristics. Finally, it lists some common applications of MOSFETs, such as in switching and amplifying electronic signals, inverters, digital circuits, high frequency amplifiers, and switch mode power supplies.

1. MOSFET

2. Classification

3. Construction
&
symbol

4. Construction of MOSFET

5. E- MOSFET CONSTRUCTION AND
WORKING
D- MOSFET CONSTRUCTION AND
WORKING

6. Drain Characteristics
Depletion Mode N channel MOSFET Enhancement Mode N channel MOSFET

7. Transfer Characteristics

8. Summary

9. TERMS BJT FET MOSFET
Device type Current controlled Voltage controlled Voltage Controlled
Current flow Bipolar Unipolar Unipolar
Terminals
Not
interchangeable
Interchangeable Interchangeable
Operational
modes
No modes
Depletion mode
only
Both Enhancement and
Depletion modes
Input
impedance
Low High Very high
Output
resistance
Moderate Moderate Low
Operational
speed
Low Moderate High
Noise High Low Low
Thermal stability Low Better High
Difference

10. Application
• MOSFET is used for switching and amplifying electronics signals in the
electronic devices.
• It is used as an inverter.
• It can be used in digital circuit.
• MOSFET can be used as a high frequency amplifier.
• It can be used as a passive element e.g. resistor, capacitor and inductor.
• It can be used in brushless DC motor drive.
• It can be used in electronic DC relay.
• It is used in switch mode power supply (SMPS).