Institute of CS & IT

Presented Honorably

to Sir Raja Tahir

•What is Diode?

•Different types of diode.

•Rectification.

Presentation outlines

What is Diode?A Diode is the simplest two-terminal unilateral semiconductor device. It allows current to flow only in one direction and blocks the current that flows in the opposite direction. The two terminals of the diode are called as anode and cathode. The symbol of diode is as shown in the figure.

The Ideal Diode Model

Anode Cathode

•Small signal Diode (Small current Diode).

• Large signal Diodes .

•Zener Diodes.

• Light Emitting Diodes (LED) .

• LASER Diode .

•PN Junction diode.

Types of Diode

Small signal Diode

These diodes assumes that the

operating point is not affected

because the signal is small.

Large Signal Diodes

The operating point in these

diodes get affected as the signal

is large.

Zener Diodes

This diode runs in reverse bias

condition when the voltage reaches the

breakdown point. A stable voltage can

be achieved by placing a resistor across

it to limit the current. This diode is used

to provide reference voltage in power

supply circuits

Light Emitting Diodes (LED)

This is the most popular kind of

diode. When it works in the

forward bias condition, the current

flows through the junction to

produce the light.

LASER Diode

This diode produces laser type

of light and are expensive as

compared to LED. They are

widely used in CD and DVD

drives.

PN Junction Diode

These diodes are used to allow current to

flow in one direction while blocking

current flow in the opposite direction.PN

junction diode is a typical diode

Rectification

The process of converting A.C

waveform into d.c waveform is called

Rectification.

Methods:

• Half-wave Rectification

• Full-wave Rectification

Half-wave Rectification

A type of rectification in which one half

cycle of the input A.C current is

converted into d.c current

Half-wave Rectification

Full-wave Rectification

A type of rectification in which both the

input cycles of A.C current is converted

into d.c current.

Full-wave Rectification

A.C Input

d.c output

Rectifier with four diodes

• One input halfcycle

Full-wave Rectification

A.C Input

d.C output

Full-wave Rectification

• Second input halfcycle

A.C Input

d.c output

Thank You