Design and implementation of efficient IIR notch filters with quantization error feedback

Straightforward methods for the design of digital notch filters are presented. The design method is based on setting a zero of the filter at a notch frequency and placing a pole in its neighborhood such that the notch width is narrow enough while keeping the group delay of the filter sufficiently flat. A technique for efficient and well-behaved implementation with fixed-point signal processors is advanced, based on the use of quantization error feedback for roundoff noise reduction. The design approach is illustrated with numerical examples, and an assembly-language program for the family of TMS320 signal processors is provided