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Hiroaki TANABE Hiroshi TANIMOTO
This paper describes a numerical design procedure of element values of RC polyphase filters with equal minima in stopband and equal ripple in passband. Determination of element values of RC polyphase filters with equal-ripple characteristic have not been solved to the best knowledge of the authors. There found a paper tackling with the problem; however, it can only give sub-optimal solutions via numerical calculation [3]. We propose a numerical element value design procedure for RC polyphase filters with equi-ripple gain in both stopband and passband by using the coefficient matching method. Some design examples are given.
Kazuhiro SHOUNO Yukio ISHIBASHI
A complex coefficient filter obtained by directly exchanging several reactance elements included in a real coefficient BPF for imaginary valued resistors is described. By using the proposed method, we obtain four varieties of complex coefficient filters. The stability problem is examined.
Kazuhiro SHOUNO Yukio ISHIBASHI
In this paper, a realization of an imaginary resistor using an ideal transformer is proposed. In the same fashion as the conventional method, a signal path is divided into a real signal path and an imaginary path. We name circuits which constitute a real signal path and an imaginary signal path, a real circuit and an imaginary circuit, respectively. An imaginary resistor is converted into an ideal transformer embedded between the imaginary circuit and the real circuit. The imaginary circuit becomes a dual circuit of the real circuit. This filter consists of terminating resistors, inductors, capacitors and ideal transformers. This prototype circuit is simulated by using operational amplifiers. A 3rd-order complex Chebyshev bandpass filter is designed and its frequency response is measured. Finally, the sensitivity property of the proposed filter is evaluated by a computer simulation.