Design of Digital Filters Simulating an LCR Filter with Node Equation

Hazaoud AHMED  Etsuro HAYAHARA  Masaki KOBAYASHI  Yoshio ITOH  

IEICE TRANSACTIONS (1976-1990)   Vol.E68   No.8   pp.535-539
Publication Date: 1985/08/25
Online ISSN: 
Print ISSN: 0000-0000
Type of Manuscript: PAPER
Category: Circuit Theory

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This paper describes a digital filter realization method by simulating an LCR filter. Having the node equation of an original LCR filter the frequency variable s is transformed into a z one using the bilinear transformation. The resulting network equation can be digitally realized with the same transfer function as the original LCR filter. Using such a method, the circuit either has a large error in the transfer response near zero frequencies or causes oscillations. A technique to avoid this problem by a simple modification of the multiplier coefficients is shown. A fifth order elliptic filter is presented with illustrative comparison to classical cascade structure.