Narrow-band and wide-band high-speed recursive digital filters using single filter frequency masking techniques

The design of single filter frequency masking recursive filters is discussed. We review the previously proposed lowpass narrow-band filters and propose a design method for highpass narrow-band filters. Wide-band filters are also discussed. The proposed approach uses several identical filters, except for periodicity, which are mapped to a single hardware structure using folding. This results in an area-efficient, pipeline/interleaved implementation with a small number of multipliers and adders at the cost of more registers. The resulting structure has a higher maximal sample frequency compared with a direct implementation of the filter, and is therefore potentially more suitable for a low-power implementation by supply voltage scaling. An example illustrates the design of a wide-band lowpass filter