# Electronics Handbook/Components/Diodes

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## Diode

Diode is a SemiConductor Device made from joining One Positive typed Semi Conductor with One Neagative Typed Semi Conductor .

- o--[N P]--o +

Diode is an Unijuction device that has two distinct polarities namely Anode which is Negative and Cathode which is Positive . Diode has a circuit symbol

## Diode's Characrteristics

### Break-over Voltage

Vd = 0.3v for Si and 0.6v for Ge

### Operation

V < Vd . I = 0 . Diode does not conduct current
V = Vd . I = 1 mA . Current starts to flow
V > Vd . I = ev . Diode conducts current exponentially

### Polarities & Biased Voltage

When Diode is connected with a voltage source in such that the polarities of the diode is in opposite with the poarities of the voltage source Diode is said to be Forward Biased and when voltage is greter than Forward biased voltage current will flow and increase exponentially with time in the direction of Pointing Arrow

When Diode is connected with a voltage source in such that the polarities of the diode is in the same with the poarities of the voltage source Diode is said to be Backward Biased Diode does not conduct current

## Diode's Types

Component Diode
PN Diode
Light Emitted Diode
Schottky Diode
Photo Diode
Varactor Diode
Zener Diode
Tunnel Diode

## Summary

Component Diode
Construction Diode is made by joining one positive typed semi conductor with one negative typed semi conductor
+ o---[P N] ---o -
Symbol
I - V Characteristics
Break Over Voltage Voltage where current is exactly 1mA
. V_d = 0.3v Ge
V_d = 0.6v Si
Conduction Diode conducts when the polarities of diode is in reverse to the polarities of voltage source and forward biased voltage is greater than the break over voltage
Non Conduction Diode does not conduct when the polarities of diode is in the same as the polarities of voltage source or forward biased voltage is less than the break over voltage
Current I = 0 V < V_d
${\displaystyle I=1mA}$ ; ${\displaystyle V=V_{d}}$
${\displaystyle I=I_{s}e^{(}{\frac {V_{d}}{V}})}$
Direction of Current flow same as arrow direction
Didoe Types PN Diode