Computationally efficient wideband filters with very narrow transition bands

The authors provide an approximate analytical characterization for a wideband lowpass filter realization using the frequency-masking approach, and extend it to the case of wideband bandpass filters. Approximate expressions for the optimal value of the interpolating factor are derived, which minimizes the total arithmetic hardware used in the overall realization. In addition, the authors derive formulae for the total number of adders and multipliers in the overall realization. The proposed two-branch realization is computationally more efficient than the conventional direct-form realization, with a moderate increase in the number of delays. The noise performance of these wideband designs compares very favorably with those of equivalent direct-form realizations.<>