Issue Details

My data acquisition device has pseudodifferential input configurations. What is a pseudodifferential input?
 

Solution

A pseudodifferential input is like a differential input in that it minimizes ground loops and noise pickup, as well as rejecting common-mode voltage. Unlike a differential input, AI0- should not vary much with time. AI0- is not intended to carry signals of interest but only to provide a DC reference point for AI0+.

With pseudodifferential inputs, the instrumentation amplifier's positive input (AI0+) is connected to the signal, and the negative input (AI0-) is connected to the negative terminal of the sensor and a ground referencing resistor. It can reduce noise pickup and reject common-mode voltage, allowing the input signal to float within the common-mode limits of the instrumentation amplifier. As well as minimize the effects of ground potential differences (ground loops) between the signal source and the device, which leads to more accurate measurements.