Selectable bandwidth filter formed from perfect reconstruction polyphase filter bank

There are many applications for digital filters that require or desire operator selectable bandwidths over a wide range of fractional bandwidth. Implementation considerations guide us to favor filters with fixed coefficients that are implemented with hardwired multipliers rather than with arbitrary multipliers. The technique described here uses only fixed, hardwired multipliers to form a pair of M-path analysis and synthesis filters. A selectable bandwidth filter is formed by masking, enabling or disabling, the connections between the output ports of the analysis filter and the input ports of the synthesis filter.