Internal wordlength reduction in RNS recursive digital filters

The possibility of designing RNS (residue number system) recursive digital filters with reduced internal wordlength is considered. For this purpose, a class of RNS filters is introduced which are not affected by coefficient and signal overflows in internal points. The proposed filter architecture consist of two independent and parallel modular processors. A complete example of RNS fifth-order low-pass filters with 8-b wordlength is developed and compared with conventional fixed-point implementations. The proposed algorithm exhibits arithmetical features similar to those of conventional ones with larger wordlengths. This result is very promising in view of the development of ASIC architectures