Question

At a constant collector current, the magnitude of base-emitter voltage decreases by 2 mV for every XX rise in temperature. Here XX is _________
1. 3° C
2. 9° C
3. 4° C
4. 1° C

Answer 1

Correct Answer - Option 4 : 1° C

Explanation-     

As the temperature of a transistor increases, the collector current will increase because:

Intrinsic semiconductor current between the collector and base increases with temperature.

Its flow through the biasing resistors drives the base more positive, increasing forward bias on the base-emitter diode.

For a silicon diode Simpson quotes an increase of 2 nA for a 10°C temperature rise.

The base-emitter voltage required for a given collector current will decrease. This decrease is about −2.5mV/°C.

NOTE-

Reverse saturation current (I_S) of the diode increases with an increase in the temperature the rise is 7%/ºC for both germanium and silicon and approximately doubles for every 10ºC rise in temperature.