Question

In a transistor output characteristics commonly used in common emitter con ig ration, the base current $I_B$, the collector current $I_C$ and the collector-emitter voltage $V_{CE}$ have values of the following orders of magnitude in the active region

• A. $I_B$ and $I_C$ both are in $\mu A$ and $V_{CE}$ in Volts
• B. $I_B$ is in $\mu A$, and $I_C$ is in $mA$ and $V_{CE}$ in Volts
• C. $I_B$ is in $mA$, and $I_C$ is in $\mu A$ and $V_{CE}$ in $mV$
• D. $I_B$ is in $mA$, and $I_C$ is in $mA$ and $V_{CE}$ in $mV$

Answer 1

The correct option is B $I_B$ is in $\mu A$, and $I_C$ is in $mA$ and $V_{CE}$ in Volts

In common emitter$\left(CE\right)$ configuration, the input current $\left(I_B\right)$ is very small, so,it is measured in micro ampere$\left(\mu A\right).$

2. If the out voltage $V_{CE}$ applied to the collector base junction is further increased, the depletion region width further increases.

3. The base region is lightly dopes as compared the collector region.So, the depletion region penetrates more into the base region and less into the collector region.

4. As a result the width of the base region decreases in turn reduces the input current. And, it means that the output current or collector current $\left(I_C\right)$ is larger as compared to the base current $\left(I_B\right)$ and so,it is measured in mili ampere$\left(mA\right)$

5. As the output voltage increases from zero volt to different voltage level, since the cut in voltage is increased above $0.7V$ so, in the active region the collector-emitter voltage$\left(V_{CE}\right)$ or output voltage is measured in volts.

It can be shown the output characteristic $CE$ configuration Curve.