FET.History of FET.types of FET.Operations of FET.Basic Information abot FET.Terminals of FEt.MOSFET.Advantages.Disadvantages.Uses of FET.

1. The FET
Field Effect Transistor

2. Field Effect Transistors
• History
The field-effect transistor was
first patented by Julius Edgar
Lilienfeld in 1926 and by Oskar
Heil in 1934

3. Basic Information
• FETs can be majority-charge-carrier
devices.
• The device consists of an active channel
through which charge carriers, electrons
or holes, flow from the source to the
drain.
• The conductivity of the channel is a
function of the potential applied across
the gate and source terminals.

4. The FET's three terminals are:
• Source (S), through which the carriers enter
the channel. Conventionally, current entering
the channel at S is designated by IS.
• Drain (D), through which the carriers leave
the channel. Conventionally, current entering
the channel at D is designated by ID. Drain-
to-source voltage is VDS.
• Gate (G), the terminal that modulates the
channel conductivity. By applying voltage to
G, one can control ID.

5. The semiconductor channel where the
current flow occurs may be either P-type
or N-type. This gives rise to two types or
categories of FET known as P-Channel and
N-Channel FETs.
Junction FET circuit symbol

6. The MOSFET
Metal Oxide Semiconductor Field
Effect Transistor

7. MOSFET
The MOSFET (Metal Oxide
Semiconductor Field Effect
Transistor) transistor is a
semiconductor device which is
widely used for switching and
amplifying electronic signals in the
electronic devices.

8. MOSFET

9. The MOSFET is a core of integrated circuit and
it can be designed and fabricated in a single
chip because of these very small sizes. The
MOSFET is a four terminal device with
source(S), gate (G), drain (D) and body (B)
terminals. The body of the MOSFET is
frequently connected to the source terminal so
making it a three terminal device like field
effect transistor. The MOSFET is very far the
most common transistor and can be used in
both analog and digital circuits.

10. More about terminals
• All FETs have source, drain, and gate terminals
that correspond roughly to
the emitter, collector, and base of BJTs.

11. • The names of the terminals refer to their
functions. The gate terminal may be thought
of as controlling the opening and closing of a
physical gate.
• This gate permits electrons to flow through or
blocks their passage by creating or eliminating
a channel between the source and drain.
• Electron-flow from the source terminal
towards the drain terminal is influenced by an
applied voltage.
• The body simply refers to the bulk of the
semiconductor in which the gate, source and
drain lie.

12. Advantages:
• One advantage of the FET is its high gate
to main current resistance.
• FET typically produces less noise than
a bipolar junction transistor (BJT), and is
thus found in noise sensitive electronics
such as tuners and low-noise amplifiers
for satellite receivers.
• It is relatively immune to radiation.

13. • It exhibits no offset voltage at zero drain
current and hence makes an excellent
signal chopper.
• It typically has better thermal stability
than a BJT. Because they are controlled
by gate charge, once the gate is closed or
opened, there is no additional power
draw.

14. Disadvantages:
• The MOSFET has a drawback of being
very susceptible to overload voltages,
thus requiring special handling during
installation.
• The fragile insulating layer of the
MOSFET between the gate and channel
makes it vulnerable to electrostatic
damage.