CE Amplifier

An amplifier a circuit which amplifies the magnitude of the input signal. Here the concept is the output should be proper replica of the amplified input signal. This  phenomenon is characterised by analysing and studying the parameters of the amplifier. The common emitter is the mostly used amplifier configuration. We use the amplifier circuits where the high voltage gain is required. For both the PNP and NPN transistors CE amplifier circuits the input is applied to the base and output is collected at the collector terminal. The common terminal for both the terminals is the emitter.

COMMON EMITTER TRANSISTOR AMPLIFIER CHARACTERISTICS
parameter	characteristics
Voltage gain	medium
Current gain	medium
Power gain	high
Input & output relationshiop	180 degrees
Input resistance	medium
Output resistance	medium

The input impedance is around 1k ohm. But it various as per the design specifications. The output impedance will be high around 10k ohm. Sometimes the output impedance would be more high. The current gain for the common emitter amplifier is denoted by the greek symbol beta and is defined as the ratio of output collector current to input base current. The change in the input base current results change in the output collector current. Here the operating point is considered as an important parameter, because the circuit works as an amplifier only if the operating point is in the active region. So to maintain the operating point in the active region proper biasing and stabilization techniques are to be used to have stable output. But if the more amount of current flows through the output terminals the output impedance may reduce. Among all the configurations the CE amplifier configuration is the best configuration because this configuration provides better current gain and voltage gain.

-------------------------------------------------------
Article By:

G Madhu

ECE Department

Sphoorthy Engineering College

Sphoorthy Engineering College