I have single-ended senors/transducers which are hooked up to a DAC in single-ended configuration. The transducers are calibrated by another company with certificates and they can output from -10V to +10V DC.
For mitigating common mode noise issues I want to convert these transducer outputs to differential ended. Currently I'm using coaxial cable with BNC connectors in single-ended earth referenced configuration and the sources/transducers are floating. I want to switch to diff. ended configuration and plan to use twisted shielded cable with BNC connectors. Below illustration roughly shows the current and planned cases:
After some research I found the following topology for single to differential conversion. LT1054 is just there to create negative supply for the opamp rails.
My questions are the following:
1) Now the voltage measured by the DAC which is Vo+ - Vo- is two tiimes the transducer's output voltage. I can see this is expected because of mirrored outputs. In this case should I reduce R3, R4, R5, R6 to 5k or simply divide the voltage by two in software end? Which is more common or convenient? (edit: I forgot to mention the DAC range is -10 to +10V so for 7V transducer output it will be in trouble to measure 14V)
2) My concern is that in this topology one solders the resistors himself. So the resistor tolerances and accuracy would effect the output. I mean if the transducer outputs 1V the diff output is 2V in simulation. That's alright and expected. But in real those resistors together with wires will not be exactly 10k. So instead of 2V it might read 2.1V which is quite large error. So Im wondering: Am I in wrong direction when trying to convert accuracy important single ended sensors to diff. ended myself this way? Or should I use a ready chip? When trying to mitigate common mode noise I dont want to introduce offset error to the transducer output by this circuit.