Question

For a BJT, the common-base current gain \(\alpha \; = \;0.98\) and the collector base junction reverse bias saturation current I_CO = 0 .6 μA. This BJT is connected in the common emitter mode and operated in the active region with a base drive current I_B = 20 μA  . The collector current I_C for this mode of operation is:
1. 0.98mA
2. 0.99mA
3. 1.0mA
4. 1.01mA

Answer 1

Correct Answer - Option 4 : 1.01mA

Concept:

Current gain β is given as:

\(\beta = \frac{\alpha }{{1 - \alpha }}\)

Collector current in terms of reverse bias saturation current is given as:

\({I_c}={β{I_B}}+{\left(1+β\right)}I_s\)

Calculation:

Given:

Is = 0.6μA

α=0.98

IB= 20µA

\(\beta = \frac{0.98}{{1 - 0.98}}=49\)

putting values,

\({I_c}={49\times{20μ{A}}}+{\left(50\right)}\times0.6μ{A}\)

\({I_c}=0.98{m}A+0.03{m}A=1.01mA\)