Finding total circuit current consumption for BJT amp

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SUMMARY

To accurately measure the total power consumed by a common base BJT amplifier, one must measure the voltage across the collector resistor (Rc) down to the emitter resistor (Re) and take a current measurement from the power supply (Vcc) to Rc. The product of these two measurements provides the total power consumption. Utilizing a small sense resistor in the power supply connection allows for precise current measurement without significant IR drop interference, following Ohm's Law for calculations.

PREREQUISITES
  • Understanding of common base BJT amplifier configurations
  • Knowledge of Ohm's Law for calculating power
  • Familiarity with circuit measurement techniques
  • Experience with using sense resistors for current measurement
NEXT STEPS
  • Research BJT amplifier biasing techniques
  • Learn about measuring voltage and current in electronic circuits
  • Explore the use of sense resistors in power measurement
  • Study the impact of IR drop in circuit design
USEFUL FOR

Electronics engineers, hobbyists designing BJT amplifiers, and anyone involved in power measurement and analysis in electronic circuits.

Physicist3
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For a common base bjt amp, would I be correct in thinking that to measure total power consumed by the circuit, you would measure voltage from Rc down to Re (inclusive) and take a current measurement from between Vcc and Rc and then multiply together?
 
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Physicist3 said:
For a common base bjt amp, would I be correct in thinking that to measure total power consumed by the circuit, you would measure voltage from Rc down to Re (inclusive) and take a current measurement from between Vcc and Rc and then multiply together?

It may depend on how you draw the circuit, and how you bias it. In this configuration below, the current consumption from the power supply should be pretty apparent:

http://autonopedia.org/wp-content/uploads/crafts-and-technology/electronics/Common_base.png

http://autonopedia.org/wp-content/uploads/crafts-and-technology/electronics/Common_base.png
 
The easiest way to measure it is to put a small sense resistor in the power supply connection (where small here means small enough to make the IR drop not an issue). Then you can calculate the current consumption from Ohm's law.
 

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