Chapter 3 Signal Connections
NI 660x User Manual 3-24 ni.com
For reflection problems that occur when the NI 660x receives the signal, use
series termination at the device driving the signal. The sum of R
S
and the
output impedance of the source is approximately 80 W. Typically, this
condition results in a value of approximately 50 W for R
S
. To use serial
termination when the source impedance is larger than 80 W, use a voltage
follower with low output impedance, and connect R
S
at the output of the
voltage follower.
Note Before using a voltage follower or series termination, use digital filtering to
eliminate measurement errors.
Figure 3-11 shows an example of parallel and series termination.
Figure 3-11. Parallel and Series Termination Example
660x
Driving Signal Driving SignalReceiving SignalReceiving Signal
Parallel Termination Series Termination
Other
Device
660x
R
s
R
P
C
P
Other
Device
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