Question

Draw the circuit diagram of $npn$ transistor in common emitter configuration. Hence describe the working method to obtain output characteristic curve.

Answer 1

Here the base terminal and collector terminals always contain positive voltages with respect to emitter terminal. If the base voltage is equal to the emitter voltage then the transistor is in OFF state. If the base voltage increases over emitter voltage then the transistor becomes more switched until it is in fully ON state. If the sufficient positive voltage is applied to the base terminal i.e. fully-ON state, then electrons flow generated and the current (IC) flows from emitter to the collector. Here the base terminal acts as input and the collector-emitter region acts as output.

By keeping the base current ($I_B$) constant, collector- emitter ($V_{CE}$) voltage is varied and the corresponding $I_C$ values are obtained. This observation is the output characteristic.