Static and Dynamic resistance of Diode | Dynamic resistance formula

Static and Dynamic resistance of Diode

In a junction diode, applied voltage (V) is not proportional to the diode current and hence it does obey Ohm’s law. So junction diode is the example of non-ohmic conductor. The resistance of a is the function of the operating current.

Diode has two possible resistances i.e.

• d.c. or static resistance of diode.
• a.c. or dynamic resistance of diode.

Static resistance of diode

D.C. or Static resistance of the diode is defined as the ratio of the d.c. voltage across the diode direct current flowing through it.

Static resistance formula

Dynamic resistance of diode

A.C. or Dynamic resistance of the diode is defined as the ratio of the small change in voltage to corresponding small change in current in the diode.

Dynamic resistance formula

For a p-n junction diode at room temperature,

But from eqn. 1, we get

For a forward biases p-n junction, I>>I_s.

Therefore,

In case of Ge semiconductor, n=1

For a reverse biased p-n junction, R_acis very large.