National Instruments BNC-2090A User Manual page 31

Highpass filters generally exhibit poorer common-mode rejection characteristics
Note
than lowpass filters because capacitors are in the series input paths. Capacitors have poorer
tolerances than resistors, and matching the input impedances is crucial for good
common-mode rejection.
© National Instruments Corporation
Figure 3-7 shows both the schematic and the component placement for a
50 kHz highpass filter placed on differential input channel 1. If the input
signal source is floating, you must place a bias return resistor in positions
A and/or B position (R28 and R27, respectively). Refer to the
Bias Resistors section for information about installing bias resistors.
+
To DAQ
Device
–
Figure 3-7. Highpass Filter on Differential Channel 1
Figure 3-8 shows both the schematic and the component placement for a
50 kHz highpass filter placed on single-ended input channel 1. Refer to the
Installing Bias Resistors
resistors.
AI 1
To DAQ
Device
Figure 3-8. Highpass Filter on Single-Ended Channel 1
R29(C) = .001 μF
C9(E) = 6.34 kΩ
R26(D) = .001 μF
section for information about installing bias
R29(C) = .0005 μF
R49(F) = 6.34 kΩ
AI GND
AI GND
3-9
Chapter 3 Signal Conditioning
Installing
AI 1
J10
AI 1
J10
BNC-2090A User Manual