Introduction to Diodes and their applications

1. Department of Electronics & Designed by Soujanya Roy, Anish Chakraborty and Raj Sekhar Goswami
Communication Engineering

2. 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

3. Introduction- Basic Concepts
 Whats a diode?
- Di+Ode
- A semiconductor device with
two terminals allowing the
flow of current in one direction
only.

4. Introduction- Basic Concepts
 What are diodes made
out of?
 Silicon
 Germanium
 GaAs

5. Introduction- Basic Concepts
 What are diodes made
 Diamond lattice and Zinc Blende
out of? Structure

6. Introduction- Basic Concepts
 Diode
Circuit
Models
Lets Browse through the three important diode circuit models

7. 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.

8. Introduction- Basic Concepts
 Diode
Circuit
Models
√ The Ideal Diode
with Barrier +
V
√ Potential
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.

9. Introduction- Basic Concepts
 Diode
Circuit
Models
√
The Ideal Diode with
Barrier Potential & Linear +
V RF
√
Forward Resistance
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.

10. Applications- Diodes & their uses
 Applications of Diodes in various
Circuits
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11. Getting into- Diodes & their uses
 Types of Diodes and their
applications
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√ A K
√ used to allow current to flow in one direction while
Are Schematic Symbol for a PN
Junction Diode
blocking current flow in the opposite direction.
P n
Representative Structure for a
PN Junction Diode

12. Getting into- Diodes & their uses
 Types of Diodes and their
applications
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√
A K
Are specifically designed to operate under reverse breakdown Schematic Symbol for a Zener
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conditions. These diodes have a very accurate and specific Diode
reverse breakdown voltage.

13. Getting into- Diodes & their uses
 Types of Diodes and their
applications
√
√ A K
Light-emitting diodes are designed with a very large bandgap
so movement of carriers across their depletion region emits Schematic Symbol for a Light-
√ Emitting Diode
photons of light energy. Lower bandgap LEDs (Light-Emitting
Diodes) emit infrared radiation, while LEDs with higher The arrows in the LED
bandgap energy emit visible light. representation indicate
emitted light.

14. Getting into- Diodes & their uses
 Types of Diodes and their
applications
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While LEDs emit light, Photodiodes are
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sensitive to received light. They are
A K
constructed so their pn junction can be
exposed to the outside through a clear
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window or lens.
• Photoconductive Mode A K
• Photovoltaic Mode
Schematic Symbols for
Photodiodes

15. Getting into- Diodes & their uses
 Types of Diodes and their
applications
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16. Getting into- Diodes & their uses
 Types of Diodes and their
applications
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17. Getting Real- Video footage
 Letstake a look at the real
diodes and their application in
circuitry
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18. Conclusion- Summing up
 Summing up all about
diodes…!!!
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19. Bibliography- References
 Thanks to the sources…!!!
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20. THE END…
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