Common-Mode Signal Rejection Considerations - National Instruments AT E Series User Manual

Chapter 4 Connecting Signals
I/O Connector
Ground-
Referenced
Signal
V
Source s
Common-
Mode
Noise and
Ground
Potential
V
cm

Common-Mode Signal Rejection Considerations

AT E Series User Manual
Figure 4-9 shows how to connect a grounded signal source to an
AT E Series device channel configured for NRSE mode.
ACH+
+
–
ACH–
Input Multiplexers
AISENSE
+
AIGND
–
Selected Channel in NRSE Configuration
Figure 4-9. Single-Ended Input Connections for Ground-Referenced Signal
Figures 4-6 and 4-9 show connections for signal sources that are already
referenced to some ground point with respect to the AT E Series device.
In these cases, the PGIA can reject any voltage caused by ground potential
differences between the signal source and the device. In addition, with
differential input connections, the PGIA can reject common-mode noise
pickup in the leads connecting the signal sources to the device. The PGIA
can reject common-mode signals as long as V
±11 V of AIGND. The AT-MIO-16XE-50 has the additional restriction
4-26
Programmable
Gain
Instrumentation
+
Amplifier
PGIA
+
Measured
–
V
m
Voltage
–
+ and V – are both within
in in
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