JYTEK NuDAQ PCI-69222, User Manual

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Hardware Information 23
Figure 2-5 shows how to connect a floating signal source to the PCI-
69222/PCI-69223 card in differential input mode. For floating signal
sources, you need to add a resistor at each channel to provide a bias
return path. The resistor value should be about 100 times the equiv -
alent source impedance. If the source impedance is less than 100
ohms, you can simply connect the negative side of the signal to
AIGND as well as the negative input of the instrumentation amplifier
without any resistors. In differential input mode, less noise couples
into the signal connections than in single-ended mode.
Figure 2-5: Floating Source and Differential Input
x
AIxH
AIxL
x = 0, ..., 31
Ground
Referenced
Signal
Source
To A/D
Converter
AIGND
+
-
Instrumentation
Amplifier
+
-
Input Multipexer