Question

A silicon PN junction is forward biased with a constant current at room temperature. When the temperature is increased by 10°C, the forward bias voltage across the PN junction  
1. Increases by 60 mV
2. Decreases by 60 mV
3. Increase by 25 mV
4. Decreases by 25 mV

Answer 1

Correct Answer - Option 4 : Decreases by 25 mV

For Si diode:

The forward bias voltage change by – 2.5mV/°C.

Thus, for 10°C change in temperature change in forward bias.

\({\rm{\Delta }}V = - 2.5\frac{{mV}}{{^\circ C}} \times 10^\circ C\;\)

\(=-25 mV\)

Note : It may be noted here that reverse saturation current doubles for every 10 °C rise in temperature