Common-emitter configuration:

The common-emitter that is abbreviated as CE transistor configuration is displayed in figure.  The transistor terminal common to both the input and the output of the circuit is the emitter in this type of configuration.  The common-emitter configuration that is also termed as the 'grounded-emitter' configuration is the most extensively used among the three configurations.

Configurations

Figure:  Common-Emitter Transistor Configuration

 The output voltage and input current of the common-emitter configuration that are the base current I_b and the collector-emitter voltage V_ce, correspondingly, are frequently considered as the independent variables in this circuit. The dependent variables of it, on the other hand, are the base-emitter voltage V_be (that is the input voltage) and the collector current I_c (that is the output current).  A plot of the output current I_c against the collector-emitter voltage V_ce for dissimilar values of I_b might be drawn for easier analysis of a input or output characteristics of transistor, as displayed in this figure of V_ce-I_c Curves.