(b), It is seen that there is a 180-degree phase shift between the input and output waveforms.
The common emitter amplifier circuit is shown above.įrom the voltage waveforms for the CE circuit shown in Fig. Thus, the amplified load resistor appears across the collector resistor. The decreasing collector-base voltage decreases the collector current in the whole collector resistor Rc. The negative half cycle decreases the forward bias voltage across the emitter-base junction. The increasing collector current makes more voltage drops across the collector load resistor RC. This leads to an increase in the flow of electrons from the emitter to a collector through the base, hence increases the collector current. When a signal is applied across the emitter-base junction, the forward bias across this junction increases during the upper half cycle. CE Amplifier Configurations Operation of Common Emitter Amplifier The arrangement is the same for a PNP transistor, but bias will be opposite w.r.t NPN transistor. In Common Emitter Amplifier Configuration, the Emitter of a BJT is common to both the input and output signal as shown below. This configuration is evenly appropriate to both the transistors like PNP and NPN transistors but NPN transistors are most frequently used due to the widespread use of these transistors. The configuration of a common emitter transistor is widely used in most electronic circuit designs. But, as the name suggests, the main attribute of the emitter circuit is familiar for both the input as well as output. This kind of amplifier includes the signal which is given to the base terminal then the output is received from the collector terminal of the circuit. In electronic circuit design, there are three kinds of transistor configurations are used like common emitter, common base, and common collector, In that, the most frequently used one is common emitter due to its main attributes. The basic symbol of the common emitter amplifier is shown below.Ĭommon Emitter Amplifier Common Emitter Amplifier Configuration The input of this amplifier is taken from the base terminal, the output is collected from the collector terminal and the emitter terminal is common for both the terminals. The common emitter amplifier is a three basic single-stage bipolar junction transistor and is used as a voltage amplifier. The signal is applied to the amplifier input and output gain is achieved. Then, the transistor should be biased to get the desired Q-point. When a transistor is used as an amplifier, the first step is to choose an appropriate configuration, in which the device is to be used. The transistor (BJT, FET) is a major component in an amplifier system. One most important constraint during the amplification is that only the magnitude of the signal should increase and there should be no changes in the original signal shape. The process of increasing the strength of a weak signal is known as Amplification. The Amplifier is an electronic circuit that is used to increase the strength of a weak input signal in terms of voltage, current, or power.
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