National Instruments NI USB-9229 - Manual (Page 12)

NI USB-9229/9239 User Guide and Specifications 12 ni.com
Each channel provides an independent signal path and ADC, enabling you
to sample all four channels simultaneously. Refer to Figure 10 for an
illustration of the circuitry for one channel.
Figure 10. Input Circuitry for One Channel
Understanding NI USB-9229/9239 Filtering
The NI USB-9229/9239 uses a combination of analog and digital filtering
to provide an accurate representation of in-band signals while rejecting
out-of-band signals. The filters discriminate between signals based on
the frequency range, or bandwidth, of the signal. The three important
bandwidths to consider are the passband, the stopband, and the alias-free
bandwidth.
The NI USB-9229/9239 represents signals within the passband, as
quantified primarily by passband ripple and phase nonlinearity. All signals
that appear in the alias-free bandwidth are either unaliased signals or
signals that have been filtered by at least the amount of the stopband
rejection.
NI USB-9229/9239
AI+
AI–
ADC
Amplifier
Overvoltage
Protection
Prefilter