Department of Electronics &
Communication Engineering
Designed by Soujanya Roy, Anish Chakraborty and Raj Sekhar Goswami
AGENDA






Introduction to the Basic concepts of
Diodes
- Whats a diode?
- What are diodes made out of?
- Diode Circuit Models
Applications of diodes in various circuits
Getting into:
- Types of diodes
- Their uses
Getting Real
- Lets take a look at the real diodes
- Video footage
Conclusion
Bibliography
Introduction- Basic Concepts
 Whats
a diode?
- Di+Ode
- A semiconductor device with
two terminals allowing the flow of
current in one direction only.
Introduction- Basic Concepts
 What
are diodes made
out of?
 Silicon
 Germanium
 GaAs
Introduction- Basic Concepts
 What
are diodes made
 Diamond lattice and Zinc Blende
out of?
Structure
Introduction- Basic Concepts
 Diode
Circuit Models
Lets Browse through the three important diode circuit models
Introduction- Basic Concepts
 Diode
√
Circuit Models
The Ideal Diode
Model
The diode is designed to allow current to flow in only one direction.
The perfect diode would be a perfect conductor in one direction
(forward bias) and a perfect insulator in the other direction (reverse
bias). In many situations, using the ideal diode approximation is
acceptable.
Introduction- Basic Concepts
 Diode
√
√
Circuit Models
The Ideal Diode with
Barrier Potential
+
V
This model is more accurate than the simple ideal diode model
because it includes the approximate barrier potential voltage.
Remember the barrier potential voltage is the voltage at which
appreciable current starts to flow.
Introduction- Basic Concepts
 Diode
√
√
√
Circuit Models
The Ideal Diode with Barrier
Potential & Linear Forward
Resistance
+
V
RF
This model is the most accurate of the three. It includes a linear forward
resistance that is calculated from the slope of the linear portion of the
transconductance curve. However, this is usually not necessary since the
RF (forward resistance) value is pretty constant. For low-power
germanium and silicon diodes the RF value is usually in the 2 to 5 ohms
range, while higher power diodes have a RF value closer to 1 ohm.
Applications- Diodes & their uses
 Applications
of Diodes in various
Circuits
√
√
√
√
√
√
√
Getting into- Diodes & their uses
 Types
of Diodes and their
applications
√
A
√
√Are used to allow current to flow in one direction while blocking
current flow in the opposite direction.
Representative Structure for a PN
Junction Diode
K
Schematic Symbol for a PN
Junction Diode
P
n
Getting into- Diodes & their uses
 Types
of Diodes and their
applications
√
√
Are specifically designed to operate under reverse breakdown
√
conditions.
These diodes have a very accurate and specific reverse
breakdown voltage.
A
K
Schematic Symbol for a Zener
Diode
Getting into- Diodes & their uses
 Types
of Diodes and their
applications
√
√
A
Light-emitting diodes are designed with a very large bandgap so
Schematic Symbol for a Lightmovement of carriers across their depletion region emits photons of
√
Emitting Diode
light energy. Lower bandgap LEDs (Light-Emitting Diodes) emit
infrared radiation, while LEDs with higher bandgap energy emit
The arrows in the LED
visible light.
representation indicate
emitted light.
K
Getting into- Diodes & their uses
 Types
of Diodes and their
applications
√
While LEDs emit light, Photodiodes are sensitive
to√received light. They are constructed so their
pn junction can be exposed to the outside
through a clear window or lens.
•√
Photoconductive Mode
• Photovoltaic Mode
A
A
K

Schematic Symbols for
Photodiodes
K
Getting into- Diodes & their uses
 Types
of Diodes and their
applications
√
√
√
Getting into- Diodes & their uses
 Types
of Diodes and their
applications
√
√
√
Getting Real- Video footage
 Lets
take a look at the real diodes
and their application in circuitry
√
√
√
Conclusion- Summing up
 Summing
√
√
√
√
√
up all about diodes…!!!
Bibliography- References
 Thanks
√
√
√
√
√
to the sources…!!!
THE END…
√
√
√
√
√