Chapter 4
Analog Input
X Series User Manual
4-16
ni.com
Figure 4-5.
Differential Connections for Floating Signal Sources with
Single Bias Resistor
Yo
u
can f
u
lly balance the signal path by connecting another resistor of
the same val
u
e between the positive inp
u
t and AI GND, as shown in
Fig
u
re 4-6. This f
u
lly balanced config
u
ration offers slightly better noise
rejection, b
u
t has the disadvantage of loading the so
u
rce down with the
series combination (s
u
m) of the two resistors. If, for example, the so
u
rce
impedance is 2 k
Ω
and each of the two resistors is 100 k
Ω
, the resistors
load down the so
u
rce with 200 k
Ω
and prod
u
ce a –1% gain error.
–
+
R i
s
ab
o
u
t
100 time
s
s
o
u
rce
imped
a
nce
of
s
en
s
or
AI GND
R
V
s
Flo
a
ting
S
ign
a
l
S
o
u
rce
AI+
AI–
AI
S
EN
S
E
MIO X
S
erie
s
Device
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