Difference Amplifier

The circuit below shows a difference amplifier using an op amp. It presents an impedance of R1 to each end of the sensor (VSEN+ - VSEN-). The gain transfer function of the difference amplifier is also shown in the figure.

diff-amp.png

Advantages:

  • Resistive isolation from the source
  • Large input voltage range is possible
  • Reject common mode noise; it's good for remote sensors
  • Simplicity

Disadvantages:

  • Resistive loading of the source
  • Input stage distortion

Sensor Examples:

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