What is Power MOSFET and Types of MOSFETs

Power MOSFET

• The long form of MOSFET is Metal Oxide Semiconductor Field Effect Transistor.
• The new power MOSFETS have improved current carrying capacity and higher off state blocking voltage capacity and they are replacing the power transistors in many applications.
• Power MOSFETS are capable of switching at very high frequencies upto about 100 kHz. This is much higher than the 10 kHz limit for the power transistors.
• A power BJT is a current controlled device. The collector current is dependent on the base current hence the current is highly dependent on the junction temperature. This is a serious disadvantage of power BJT.
  
• To overcome this disadvantage, we can use a voltage controlled device such as a power MOSFET. The other advantage of MOSFET is that it requires only a small input current.
• Some of the important features of a power MOSFET are as follows :

Features of power MOSFET

1. Low input current.
2. It is a voltage controlled device.
3. Switching speed is very high.
4. Switching speeds are of the order of nanoseconds.
5. They do not have the problem of second s breakdown.

Types of MOSFETS

MOSFETS are of three types :

1. Depletion type MOSFET.
2. Enhancement type MOSFET.
3. Power MOSFETS

MOSFET is a three terminal device. The terminals are Drain, Source and Gate.