What is MOSFET
Metal
oxide silicon Field impact electronic transistor is abbreviated as MOSFET.
It is just a unipolar electronic transistor AN used as an electronic switch and
to amplify electronic signals. The device has 3 terminals consisting of a
supply, gate and drain. Apart from these terminals there's a substrate usually
known as the body that is usually connected to the supply terminal for sensible
applications.
In
recent years, its discovery has led to the dominant usage of those devices in
digital integrated circuits because of its structure. The Silicon di-oxide
(SiO2) layer acts as an insulator and provides electrical isolation between the
gate and an active channel between the source and the drain which provides high
input electrical resistance that is sort of infinite so capturing all the
signal.
Working Principle of MOSFET
It is
fabricated by the oxidation of silicon substrates. It works by altering the
width of the channel through which the movement of charge carriers (electrons
for N-channel and holes for P-channel) occurs from source to drain. The gate
terminal is insulated whose voltage regulates the conduction of the device.
Applications of MOSFET
MOSFET
amplifiers ar extensively utilized in radio frequency applications.
It
acts as a passive part like electrical device, capacitor and inductor.
DC
motors can be regulated by power MOSFETs.
High
switching speed of MOSFETs make it an ideal choice in designing chopper
circuits.
Types of MOSFET
On
the basis of Operational Mode, MOSFETs can be classified into two types.
• Enhancement Type MOSFETs
• Depletion Type MOSFETs
Enhancement Type MOSFET
In
this mode, there's no conductivity at zero voltage which suggests it's closed
or “OFF” by default as there's no existing channel. When the gate voltage is
increased over the supply voltage, the charge carriers (holes) shifts away
leaving behind the electrons and thus a wider channel is established.
The
gate voltage is directly proportional to the present i.e. as the gate voltage
increases the current increases and vice versa.
Depletion Type MOSFET
In
this sort, the channel is already established and it is evident that the
conduction occurs even at zero voltage and it is open or “ON” by default.
Unlike improvement sort, here the channel is depleted of charge carriers to
reduce the width of the channel.
The
gate voltage is reciprocally proportional to the present i.e. as the gate
voltage increases the current decreases.
Advantages of MOSFET
• MOSFETs
provide excellent efficiency while operating at lower voltages.
• Absence
of gate current results in high input impedance producing high switching speed.
• They
operate at lower power and draws no current.
Disadvantages of MOSFET
• The
thin oxide layer make the MOSFETs vulnerable to permanent damage when evoked by
electrostatic charges.
• Overload
voltages makes it unstable.
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