© National Instruments
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2-21
Figure 2-15.
AI Differential Configuration with Balanced Bias Resistors
Lowpass Filtering
Lowpass filters highly or completely attenuate signals with frequencies above the cut-off
frequency, or high-frequency stopband signals. Lowpass filters do not attenuate signals with
frequencies below the cut-off frequency, or low-frequency passband signals. Ideally, lowpass
filters have a phase shift that is linear with respect to frequency. This linear phase shift delays
signal components of all frequencies by a constant time, independent of frequency, thereby
preserving the overall shape of the signal.
In practice, lowpass filters subject input signals to a mathematical transfer function that
approximates the characteristics of an ideal filter. By analyzing the Bode Plot, or the plot that
represents the transfer function, you can determine the filter characteristics.
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