TY - JOUR

T1 - Approximation of group delay response of allpass filters using weighted least square method

AU - Okuda, Masahiro

AU - Matsuyama, Kojiro

AU - Ikehara, Masaaki

PY - 1996/6

Y1 - 1996/6

N2 - Allpass filters with prescribed group-delay response are useful in compensating such response. In general, the approximation of group-delay response is formulated as a nonlinear problem; thus, its approximation becomes difficult. The design methods with nonlinear optimization have the problem that initial values of filter coefficients are needed and heavy computation is required. The design method is simplified in the conventional method where magnitude response is approximated instead of group-delay response, but the approximation error is increased in the indirect methods. This paper proposes a method in which group-delay response is approximated by a linear function and optimal solution is obtained in the least square sense by iteratively solving the linear equations. This method has the merit that the error of group-delay response is directly evaluated. Moreover, applying Lawson's algorithm to this method, an equiripple solution can be obtained and maximum value of error can be decreased.

AB - Allpass filters with prescribed group-delay response are useful in compensating such response. In general, the approximation of group-delay response is formulated as a nonlinear problem; thus, its approximation becomes difficult. The design methods with nonlinear optimization have the problem that initial values of filter coefficients are needed and heavy computation is required. The design method is simplified in the conventional method where magnitude response is approximated instead of group-delay response, but the approximation error is increased in the indirect methods. This paper proposes a method in which group-delay response is approximated by a linear function and optimal solution is obtained in the least square sense by iteratively solving the linear equations. This method has the merit that the error of group-delay response is directly evaluated. Moreover, applying Lawson's algorithm to this method, an equiripple solution can be obtained and maximum value of error can be decreased.

KW - Allpass filter

KW - Equiripple approximation

KW - Group-delay response

KW - Weighted least square method

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U2 - 10.1002/ecjc.4430790606

DO - 10.1002/ecjc.4430790606

M3 - Article

AN - SCOPUS:0030168403

SN - 1042-0967

VL - 79

SP - 60

EP - 69

JO - Electronics and Communications in Japan, Part III: Fundamental Electronic Science (English translation of Denshi Tsushin Gakkai Ronbunshi)

JF - Electronics and Communications in Japan, Part III: Fundamental Electronic Science (English translation of Denshi Tsushin Gakkai Ronbunshi)

IS - 6

ER -