Differential Connections for Ground-Referenced Signal Sources

The following figure shows how to connect a ground-referenced signal source to a channel.

With this type of connection, the instrumentation amplifier rejects both the common-mode noise in the signal and the ground potential difference between the signal source and the device ground, shown as V_cm in this figure.

Common-Mode Signal Rejection Considerations

The instrumentation amplifier can reject any voltage caused by ground potential differences between the signal source and the device. In addition, the instrumentation amplifier can reject common-mode noise pickup in the leads connecting the signal sources to the device. The instrumentation amplifier can reject common-mode signals as long as V+_in and V–_in (input signals) are both within the working voltage range of the device.