Variable bandwidth M-path filter with fixed coefficients formed by M-path polyphase filter engines

Software defined radios require selectable bandwidth digital filters to process the many different bandwidth signals pulled from or inserted into the ether. Implementation considerations favor fixed length digital filters with fixed coefficients that can be implemented with hardwired multipliers. This paper describes two filter architectures that use M-path polyphase partitions to implement variable bandwidth filters with fixed coefficients and with fixed computational resources.