Common Emitter Configuration:-

• In common emitter configuration input is applied between base and emitter and out put is taken from collector and emitter. In this configuration emitter is common to both input and output circuits. Common emitter configuration for NPN transistor is given below.

• In the above figure the voltage VBB  forward baises the base-emitter junction and VCC is used to reverse bias the collector base junction. In the CE configuration the input voltage is the base-emitter voltage and output voltage is the colletor-emitter voltage. The input current is IB and output current is IC.

Experimental set-up to plot input/output characteristics of CE BJT amplifier:-

• A transistor in a common emitter configuration, has two important characteristics namely Input characteristics and output charactristics. The experimental set-up to plot input/output characteristics of CE BJT amplifier is shown in figure below.

INPUT CHARACTERISTICS:

• The input characteristics shows the relation between the base current IB and base emitter voltage VBE for fixed values of collector emitter voltage VCE. The input characteristics is shown in figure below.