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.

OUTPUT CHARACTERISTICS:

• The output characteristics shows the relation between the collector current IC and Collector voltage VCE for fixed values of IB. This characteristics is often called as collector characteristics.
• The output characteristics of common emitter configuration consists of three regions. They are Active, Saturation, and Cut-off which are shown in figure below.