Electronics Handbook/Components/Diodes

Diode

Diode is a SemiConductor Device made from joining One Positive type Semi Conductor with One Negative Type 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

I V Curve

Break-over Voltage

V_d = 0.3v for Si and 0.6v for Ge

Operation

V < V_d . I = 0 . Diode does not conduct current

V = V_d . I = 1 mA . Current starts to flow

V > V_d . I = e^v . 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 polarities 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 polarities 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 $I=1mA$ ; $V=V_{d}$ $I=I_{s}e^{(}{\frac {V_{d}}{V}})$
Direction of Current flow	same as arrow direction
Diode Types	PN Diode Light Emitted Diode Schottky Diode Photo Diode Varactor Diode Zener Diode Tunnel Diode

Reference

• Diode