Question

The biasing circuit has a stability factor of 50. If due to temperature change, ${{I}_{CBO}}$ changes by 1 μA, then ${{I}_{C}}$ will change by
A. 100 μA
B. 10 μA
C. 25 μA
D. 50 μA

Answer 1

Biasing is an important part of the Transistor circuit and is usually done to achieve the desired operation or the desired output.

Complete step by step answer:
It is given that the stability factor is 50. Let us represent it by S. Also given that due to temperature change results in change ${{I}_{CBO}}$ by I μA. Here ${{I}_{CBO}}$ refers to the collector current with collector junction reverse biased and base open-circuited. We need to find the change in collector current, ${{I}_{C}}$
S=50
${{I}_{CBO}}$=1 μA
${{I}_{C}}$=?
We know that the stability factor is given by, $S=\dfrac{{{I}_{C}}}{{{I}_{CBO}}}$
So ${{I}_{C}}=S{{I}_{CBO}}$
${{I}_{C}}=50\times 1=50$ μA

So, the correct answer is “Option D”.

Additional Information:
A transistor is made to make the emitter-base junction forward biased and collector-base junction reverse biased, or emitter-base junction reverse biased and collector-base junction forward biased. The circuit which provides biasing to the transistor is called biasing circuit. The operating point of the transistor is mainly affected by the change in temperature. The need for stabilizing the transistor arises due to the change in temperature or due to individual variations in the circuit. Also thermal runaway affects working of a transistor.

Note:
The stability factor is a measure of the change in collector current with changes in reverse saturation current. It is an important component of the transistor and usually stability factor less than 25 is suitable for transistors to work efficiently.