Why using interpolation can simplify required analog circuit

[paladinzlp]

Why using intrpolation can simplify the required analog circuit?
Such as analog filter's -3db bandwidth fB=fu/2
If we use the interpolator, how to change the filter's gain(0) and -3db bandwidth?

 

[Kral]

Re: Why using interpolation can simplify required analog cir

An analog anti-aliasing filter must attenuate any frequencies that are above the Nyquist frequency (half the sampling frequency). By using interpolation, you effectively increase the sampling rate. If (without interpolation) the Nyquist frequency is close to the highest frequency of interest, then an analog filter with a very sharp transition region is required. By increasing the effective sampling frequency, you move the aliased portion of the digital frequency response farther from the highest frequency of interest. This means that the analog anti-aliasing filter can have a higher cutoff frequency and a gentler slope (lower filter order).

Regards,
Jon