Diodes

Analog Electronic : Diodes

Presented by: - Mohamed Fdaili

- Amina Zakani

- Chaimaa Oukrati

Framed by: Mr.A.Neddami

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Outline

Conclusion

Diode applications

Types of diodes

Diode characteristics

What is a diode ?

P-N Junction

Introduction

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SEMICONDUCTOR

N-TYPE

P-TYPE

Introduction

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The P-N junctionWhen P-type and N-type materials are joined , this forms a P-N junction.

Impurity atoms(fixed)

p - type material

n - type material

Holes (mobile carriers)

Electrons (mobile carriers)

Electrons (negative charge

carriers)

Holes (positive charge

carriers)

Depletion

layer

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Forward and reverse bias

When forward biased, a diode acts as a conductor and current flows. When reverse biased, a diode acts as an insulator and no current

flows.

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what is a diode ?

It is an electronic device that ideally conducts in only one direction.

Actual Features :

Electrical Symbol :

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Ideal Diode Model (without threshold )

Diode Characteristics

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Ideal Diode Model ( with threshold)

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Real diode ( with threshold and resistance)

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The Ideal Diode Equation

s

I IqV

kT

where

I diode current with reverse bias

q coulomb the electronic ch e

keV

KBoltzmann s cons t

0

0

19

5

1

1602 10

8 62 10

exp ,

. , arg

. , ' tan

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Types of diodes• Light Emitting Diode (LED)

• Avalanche Diode.

• Laser Diode.

• Schottky Diode.

• Photo Diode.

• Varicap Diode or Varactor Diode.

• Zener Diode.

• Rectifier Diode.

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Logic gates : Diodes can be combined with other components to

construct AND and OR logic gates. This is referred to as diode logic.

Temperature measurement : A diode can be used as a temperature measuring device,

since the forward voltage drop across the diode depends on temperature, as in a Silicon band gap temperature sensor.

Power conversion : Rectifiers are constructed from diodes, where they are

used to convert alternating current (AC) electricity into direct current (DC).

Diode Applications

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Principle of rectifying

Rectifiers

The use of diodes as Rectifiers

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Two types of rectification :

a)Half-wave rectifier The simplest rectifier circuit is called the ‘Half-Wave’ rectifier

as it only converts one half cycle.

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The supply voltage is given by: Vin =Vm sinΩt ;Ω=2πf = 2 π /T

The waveforms for source voltage Vin and output voltage Vout are :

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Output DC voltage :

Vave =Vm/ Iave=Vave/R

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b) Full-wave rectifier Two diodes : The full wave rectifier consists of two diodes and a resister as

shown in Figure:

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DC voltage output:

Vave =2Vm/ Iave=Vave/R

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Four diodes :

positive alternation

20 Output DC voltage: Vave =2Vm/

Negative alternation

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with capacitor filter :

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Dc power supply circuit

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conclusion

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That's All.Thank You for Your Attention