BJT: Common Collector Configuration (Input and Output Characteristics) Explained
ALL ABOUT ELECTRONICS・6 minutes read
The common collector configuration of the BJT involves the input between the base and collector terminals and the output between the emitter and collector terminals. The current gain, denoted by gamma, offers high input impedance, low output impedance, high current gain, low voltage gain, and low power gain.
Insights
- In the common collector configuration of a BJT, the collector terminal is common, with input between the base and collector and output between the emitter and collector. During AC analysis, DC sources are ignored, and the circuit exhibits specific biasing conditions for amplifier functionality.
- The current gain (gamma) in the common collector setup is crucial, as it determines the relationship between emitter and base currents, impacting input and output impedance, current gain, voltage gain, and power gain characteristics significantly.
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Recent questions
What is the common collector configuration of a BJT?
The common collector configuration of a BJT involves the collector terminal being common between the input and output sides, with the input applied between the base and collector terminals, and the output measured between the emitter and collector terminals.
How are DC voltage sources treated during AC analysis of a BJT?
During AC analysis of a BJT, DC voltage sources are considered zero, grounding the collector terminal, while the base-emitter junction is forward biased and the collector-base junction is reverse biased for amplifier use.
What are the currents involved in the common collector BJT circuit?
In the common collector BJT circuit, the base current serves as the input current, while the emitter current acts as the output current. Additionally, DC voltages Vcb and Vce are present on the input and output sides respectively.
What do the output characteristics of a common collector BJT show?
The output characteristics of a common collector BJT depict the relationship between emitter current Ie and voltage Vce, resembling the common-emitter configuration, providing valuable insights into the behavior of the circuit.
What are the key features of the current gain in a common collector BJT configuration?
The current gain of the common collector configuration, denoted by gamma, is the ratio of emitter current to base current. This configuration offers high input impedance, low output impedance, high current gain (β+1), low voltage gain, and low power gain, making it suitable for specific applications requiring these characteristics.
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Summary
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Common Collector BJT Configuration: Characteristics and Analysis
- Common collector configuration of the BJT involves the collector terminal being common between the input and output sides, with the input applied between the base and collector terminals, and the output measured between the emitter and collector terminals.
- During AC analysis, DC voltage sources are considered zero, grounding the collector terminal, while the base-emitter junction is forward biased and the collector-base junction is reverse biased for amplifier use.
- The direction of currents in the circuit involves base current as input current and emitter current as output current, with DC voltages Vcb and Vce on the input and output sides respectively.
- Output characteristics show the relationship between emitter current Ie and voltage Vce, resembling common-emitter configuration, while input characteristics depict the relationship between base current Ib and voltage Vcb.
- The current gain of the common collector configuration, denoted by gamma, is the ratio of emitter current to base current, providing high input impedance, low output impedance, high current gain (β+1), low voltage gain, and low power gain.
