A three wire source has differential output but uni-polar(only one signal wire varies wrt AGND). Ground wire is AGND, the the other two is signal SG and the reference SGref. I'm trying to amplify the transducer signal with a gain of ten by using a non-inverting amplifier.

Since the transducer is not single ended output I'm bit confused. Which topology is correct?


simulate this circuit – Schematic created using CircuitLab

At page 41 here shows the differential wiring of channels and at page 37 it says:

The transducer outputs are designed to work with a differential input to the DAQ system for best performance. Transducer outputs are ground-referenced differential signals. The output impedance of each DAQ signal is 100Ω

(I checked the output and only SG moves wrt to AGND but not SEGref so I think it is unipolar even though differential ended)

  • \$\begingroup\$ Try simulating it and add common-mode noise equally onto both feed wires via a 1 nF capacitor. \$\endgroup\$ – Andy aka Feb 15 at 12:25
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    \$\begingroup\$ It's better to use an opamp connected to amplify differentially when you're using a differential source. \$\endgroup\$ – Neil_UK Feb 15 at 12:28
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    \$\begingroup\$ @Neil_UK Do you mean differential amplifier like this topology circuitstoday.com/wp-content/uploads/2011/11/… ?? \$\endgroup\$ – user1999 Feb 15 at 12:29
  • \$\begingroup\$ Which transducer (datasheet) and what is your DAQ ? \$\endgroup\$ – Marko Buršič Feb 15 at 13:42
  • \$\begingroup\$ First circuit will create contention between the feedback and the input signal. I think the second one is the correct option. If you want to use both the differential outputs of the transducer use fully differential design, otherwise an amplifier without feedback. \$\endgroup\$ – sarthak Feb 15 at 14:05

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