Generalized digital Butterworth filter design

  • Authors:
  • I. W. Selesnick;C. S. Burrus

  • Affiliations:
  • Dept. of Electr. & Comput. Eng., Rice Univ., Houston, TX, USA;-

  • Venue:
  • ICASSP '96 Proceedings of the Acoustics, Speech, and Signal Processing, 1996. on Conference Proceedings., 1996 IEEE International Conference - Volume 03
  • Year:
  • 1996

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Abstract

This paper presents a formula-based method for the design of IIR filters having more zeros than (nontrivial) poles. The filters are designed so that their square magnitude frequency responses are maximally-flat at /spl omega/=0 and at /spl omega/=/spl pi/ and are thereby generalizations of classical digital Butterworth filters. A main result of the paper is that, for a specified half-magnitude frequency and a specified number of zeros, there is only one valid way in which to split the zeros between z=-1 and the passband. IIR filters having more zeros than poles are of interest, because often, to obtain a good trade-off between performance and the expense of implementation, just a few poles are best.