Ti. Laakso et al., DESIGN AND IMPLEMENTATION OF EFFICIENT IIR NOTCH FILTERS WITH QUANTIZATION-ERROR FEEDBACK, IEEE transactions on instrumentation and measurement, 43(3), 1994, pp. 449-456
Straightforward methods for the design of digital notch filters are pr
esented. 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 th
e notch width is narrow enough while keeping the group delay of the fi
lter sufficiently flat. A technique for efficient and well-behaved imp
lementation with fixed-point signal processors is advanced, based on t
he use of quantization error feedback for roundoff noise reduction. Th
e design approach is illustrated with numerical examples, and an assem
bly-language program for the family of TMS320 signal processors is pro
vided.