片側接地の虚数抵抗を用いた複素RⁱCRフィルタの一構成

抄録

In this paper, a synthesis of a complex RⁱCR filter is proposed. The proposed prototype filter includes terminating resistors, floating capacitors and grounded imaginary resistors only. Because the proposed RⁱCR filter includes no floating imaginary resistors, we can reduce the active elements when we realize the filter using OTA's and capacitors. The proposed prototype filter is obtained through a frequency transformation and an equivalent transformation using imaginary gyrators. Using imaginary gyrators composed of imaginary resistors, we can transform all the inductors into capacitors. The condition for reducing the floating type imaginary resistors is described. The proposed method is based on symmetry of the circuit configuration. The proposed method can be applied to not only odd-order filters but also even-order filters. As an example, a 5th-order complex RⁱCR filter is designed. The proposed filter is compared with the conventional ones from the view points of the gain characteristics, the number of the required elements and element value spread.