リープフロッグ形構成に基づく3相複素フィルタの構成とそのGB積補償

概要

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Recently, three-phase complex filters attract attention because the number of required elements of the three-phase complex filter is lower than that of the four-phase (balanced) complex filter. In this paper, three-phase complex filters based on a leapfrog configuration are realized. The method for removing the inverter is proposed. The resulting circuit can be realized by using 3n operational amplifiers for n-th order complex filter. It is shown that the sensitivity of the proposed circuit is lower than that of the conventional one. The deviation of the passband response from the ideal one is due to the finite gain bandwidth of operational amplifiers. By taking the finite gain bandwidth of operational amplifiers into account, it is shown that the passband response of the proposed circuit is improved. The validity of the proposed method is confirmed through both of computer simulation and experiment. The experimental circuit exhibits complex bandpass characteristics (18-22kHz) and an image rejection ratio of 60.91dB.