Op-Amp vs Precision Resistor: Which is Better for I-to-V Conversion?

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SUMMARY

The discussion focuses on the comparison between using a transimpedance amplifier and a precision resistor for I-to-V conversion in applications involving low AC currents (1nA-10nA) at frequencies up to 10kHz. A transimpedance amplifier is preferred as it presents a low impedance load, minimizing the impact on the current being measured. In contrast, a precision resistor may introduce measurement errors due to voltage drop affecting the current. The choice of method significantly influences the accuracy of the voltage output for further processing.

PREREQUISITES
  • Understanding of transimpedance amplifiers
  • Knowledge of precision resistors and their specifications
  • Familiarity with AC current measurement techniques
  • Basic principles of signal processing
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  • Research the design and application of transimpedance amplifiers
  • Explore the specifications and selection criteria for precision resistors
  • Learn about AC current measurement techniques and their limitations
  • Investigate signal processing methods for low-level voltage signals
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Electrical engineers, circuit designers, and anyone involved in low-level signal processing and measurement applications.

riie
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Hi all,

What is the difference of using an op-amp(transimpedance) vs a precision resistor to convert I-to-V?

I am trying to linearly amplify a 1nA-10nA AC current with frequency of 10khz and below to a AC voltage and be passed to other circuitry for further processing.

Thank you for the help, in advance.
 
Engineering news on Phys.org
If you use a precision resistor, the voltage across it may affect the current that you are trying to measure. A transimpedance amplifier will, effectively, be present a low impedance load to your current source and not affect the current. Of course, using a low enough resistor and then measuring a very small voltage would be an alternative. . . . .
 

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