An Active RC Filter Based on Simulation of Semi-Uniformly Dissipative LC Filters


IEICE TRANSACTIONS (1976-1990)   Vol.E72   No.1   pp.23-28
Publication Date: 1989/01/25
Online ISSN: 
Print ISSN: 0000-0000
Type of Manuscript: PAPER
Category: Analog Signal Processing

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A new class of active circuits for realization of all-pole low-pass characteristics is proposed. The proposed circuit simulates the doubly terminated ladder filters realized by lossless inductors and lossy capacitors. The number of required operational amplifiers is about two thirds that of the conventional leapfrog realization. First, the synthesis method of an LC ladder filter with lossy capacitors is described. Second, the relations between the voltage and the current of the above-mentioned LC filter are derived and circuits for realizing these relations and a method for synthesizing an odd-order filter are shown. Finally, a fifth-order low-pass filter is designed and it is shown that the measured response shows a good agreement with the theoretical value. Furthermore, the element sensitivity is estimated by a computer and it is shown that the sensitivity of the proposed circuit is lower than that of the conventional leapfrog circuit.