Improvement of Group Delay and Reduction of Computational Complexity in Linear Phase IIR Filters

  • Varasumanta, Saranuwaj (Information Engineering Dept., King’s Mongkut Institute of Technology Ladkrabang) ;
  • Sookcharoenphol, Dolchai (Information Engineering Dept., King’s Mongkut Institute of Technology Ladkrabang) ;
  • Sriteraviroj, Uthai (Information Engineering Dept., King’s Mongkut Institute of Technology Ladkrabang) ;
  • Janjitrapongvej, Kanok (Information Engineering Dept., King’s Mongkut Institute of Technology Ladkrabang) ;
  • Kanna, Channarong (Information Engineering Dept., King’s Mongkut Institute of Technology Ladkrabang)
  • 발행 : 2003.10.22

초록

A technique for realizing linear phase IIR filters has been proposed by Powell-Chau which gives a real-time implementation of H(z-1).H(z), where H(z) is a causal nonlinear phase IIR filter. Powell-Chau system is linear but not timeinvariant system. Therefore, that system has group delay response that exhibits a minor sinusoidal variation superimposed on a constant value. In the signal processing, this oscillation seriously degrade the signal quality. Unfortunately, that system has a large sample delay of 4L and also more computational complexity. Proposed system is present a reduced computational complexity technique by moved the numerator polynomial of H(1/z) out to cascade with causal filter H(z) and remain only all-pole of H(1/z), then applied truncated infinite impulse response to finite with truncated IIR filtel $H_L$(z) and L sample delay to subtract the output sequence from the top and bottom filter. Proposed system is linear time invariance and group delay response and total harmonic distortion are also improved.

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