Semiconductor Electronics Part 2

The common emitter amplifier circuit is shown below An amplifier is a device which is used to amplify the amplitude of input signals and produce an amplified version as output. In CE-configuration base is input terminal, collector is output terminal and emitter is common (grounded).
For a proper operation of amplifier, the emitter base junction is forward biased and collector base junction is reversed biased. As amplifier amplifies the input signal, therefore the current gain and voltage gain of circuit should be high.
To get higher current gain and voltage gains, the circuit should operate in active region as in active region for CE-circuit,
IC=βIB
The output current at collector is β times the input current at base.
Thus, the transistor must operate only in active region.