What is Common Emitter Configuration in Transistor Amplifier?
Hey, in this article we are going to know what is common emitter configuration, how a common emitter configuration is made, and why a common emitter configuration is required for a Bipolar Junction Transistor-based amplifier. There are huge applications and important uses of common emitter amplifiers in electronics engineering. We know that a bipolar junction transistor or BJT has a total of three terminals - 1. Collector 2. Base and 3. Emitter. So, it is clear that the common-emitter configuration is completely related to the Bipolar junction transistor only. In both NPN and PNP bipolar transistors, a common emitter configuration is possible.
What is a Common Emitter?
In simple words, when the emitter terminal of the bipolar junction transistor is connected with both input and output circuits as a common terminal then it will be called a common emitter. The emitter terminal is also connected to the ground, so the common emitter configuration is also called grounded emitter configuration. In short, the common-emitter configuration is also called CE configuration.
A common emitter amplifier can be used as a single-stage powerful voltage amplifier. In the common emitter configuration, the Base to Emitter terminals are used for input and Collector to Emitter Terminals are used for output.
Common Emitter Configuration Description
There are three basic configurations to connect the bipolar junction transistor in amplifier circuits. Those configurations are - 1. Common Emitter Configuration 2. Common Base Configuration and 3. Common Collector Configuration
Common emitter amplifiers mainly act as voltage amplifiers. Common emitter configuration provides high current gain, medium input resistance, and high output resistance.
Here you can see the common-emitter circuit.
You can see, the input signal is applied across the base and emitter terminals whereas the output signal is produced across the collector and emitter terminals. So, the base terminal is used as input, the collector terminal is used as output, and the emitter terminal is used as common for both. The connection of polarity will be different for PNP and NPN Transistors. As the input resistance of the common emitter amplifier is medium so it consumes current when the input voltage is applied but as the output resistance is high, so it cannot circulate a high current in its output circuit.
The base current amplification factor is defined as the ratio of the output and input current. Generally, the base current amplification factor of a common emitter configuration is measured by the division of the changes in collector current with respect to the base current.
Common Emitter Configuration Characteristics
1. CE configuration has medium input resistance or impedance and high output resistance or Impedance.
2. Common emitter configuration provides high current gain.
3. In the common emitter configuration, the output waveform is 180 degrees or reverse to the input waveform.
4. Common emitter connection produces high leakage current through the emitter terminal to the ground.
5. The bandwidth of a common emitter amplifier is low due to the miller effect.
6. When the base current is constant then the collector current will increase with the increase of voltage across the collector and emitter.
Common Emitter Applications and Use
The common emitter configuration is mainly used for audio signal processing so you can see its applications in low-frequency voltage amplifiers and radio frequency circuits.
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What is Common Emitter Configuration in Transistor Amplifier?
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August 25, 2021
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Reviewed by Author
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August 25, 2021
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