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

DIODES AND THEIR APPLICATIONSDesigned by Soujanya Roy, Anish Chakraborty and Raj Sekhar Goswami

Department of Electronics &Communication Engineering

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

DIODES AND THEIR APPLICATIONS

Introduction- Basic Concepts

Whats a diode? - Di+Ode - A semiconductor device

with two terminals allowing the flow of current in one direction only.


CIRCUIT SYMBOL


What are diodes made out of?

Silicon Germanium GaAs


} Diamond Lattice Structure

Zincblende Structure


What are diodes made out of?


Diamond lattice and Zinc Blende Structure

• In both the diamond lattice and zincblend lattice, each atom shares its valence electrons with its four closest neighbors. This sharing of electrons is what ultimately allows diodes to be build. When dopants from groups 3 or 5 (in most cases) are added to Si, Ge or GaAs it changes the properties of the material so we are able to make the P- and N-type materials that become the diode.

Introduction- Basic Concepts Diode Circuit

Models


Ideal Diode Model

The Ideal Diode with Barrier Potential

The Ideal Diode with Barrier Potential and Linear Forward Resistance

Lets Browse through the three important diode circuit models


Ideal Diode Model



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.

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Models


Models


Ideal Diode Model




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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.


Models


Ideal Diode Model



The Ideal Diode with Barrier Potential & Linear Forward Resistance

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√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.

+V RF

Applications- Diodes & their uses

Applications of Diodes in various Circuits


Reverse voltage Protection

Rectifying Display Light Sensing

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Getting into- Diodes & their uses

Types of Diodes and their applications


THE BASIC SEMICONDUCTOR DIODE

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PN Junction Diodes:

Are used to allow current to flow in one direction while blocking current flow in the opposite direction.

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Schematic Symbol for a PN Junction Diode

P nRepresentative Structure for a PN Junction Diode




THE ZENER DIODE

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√ Schematic Symbol for a Zener Diode

A KAre specifically designed to operate under reverse breakdown conditions. These diodes have a very accurate and specific reverse breakdown voltage.




THE LIGHT EMITTING DIODES (LEDS)

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Light-emitting diodes are designed with a very large bandgap so movement of carriers across their depletion region emits photons of light energy. Lower bandgap LEDs (Light-Emitting Diodes) emit infrared radiation, while LEDs with higher bandgap energy emit visible light.

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Schematic Symbol for a Light-Emitting Diode

The arrows in the LED representation indicate emitted light.




THE PHOTO DIODES

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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

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Schematic Symbols for Photodiodes

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DIODE AS A RECTIFIER:

HALF WAVE RECTIFIER

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DIODE AS A RECTIFIER:

FULL WAVE RECTIFIER

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Getting Real- Video footage

Lets take a look at the real diodes and their application in circuitry


VIDEO FOOTAGE

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Conclusion- Summing up

Summing up all about diodes…!!!


Unidirectional device permitting easy flow of current in one direction.

Semiconductor diode basically a pn junction diode.

Diode circuit models, Ideal diode: two terminal polarity sensitive device. Forward bias: Zero Resistance; Reverse bias : infinite resistance.

Brief Insight of various diodes and their uses and applications in different circuits.

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Bibliography- References

Thanks to the sources…!!!


Electronic Devices and Circuits – JB GUPTA http://en.wikipedia.org www.google.com Analog Electronics Tutorial Series DIODES,

Kristin Ackerson, Virginia Tech EE, Spring 2002

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http://en.wikipedia.org/

http://www.google.com/

THE END…


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THANK YOU AND HAVE A NICE DAY…!!!

- SOUJANYA ROY, ANISH CHAKRABORTY AND RAJ SEKHAR GOSWAMI

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

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