What Is a Pseudodifferential Input?

Issue Details

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

Solution

Pseudodifferential signal connections reduce noise pickup and reject common-mode voltage, allowing the input signal to float within the common-mode limits of the instrumentation amplifier. 

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.

Pseudodifferential inputs minimize the effects of ground potential differences (ground loops) between the signal source and the device, which leads to more accurate measurements.

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+.