Diode Operating conditions

Posted by AJ On Tuesday, 9 July 2013 0 comments

• No Bias

• Forward Bias

• Reverse Bias

No bias condition

• No external voltage is applied: VD = 0V and no current is flowing ID = 0A.

Only a modest depletion layer exists

Reverse bias condition

External voltage is applied across the p-n junction in the opposite polarity of the p- and ntype

materials.

• This causes the depletion layer to widen.

• The electrons in the n-type material are attracted towards the positive terminal and the

‘holes’ in the p-type material are attracted towards the negative terminal.

Forward Bias Condition

• External voltage is applied across the p-n junction in the same polarity of the p- and ntype

materials.

• The depletion layer is narrow.

• The electrons from the n-type material and ‘holes’ from the p-type material have

sufficient energy to cross the junction.

• Actual v-i characteristics is as shown in fig below

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