| Summary: | 博士 === 國立中央大學 === 電機工程學系 === 104 === In order to save the valuable circuit size and reduce the mismatching loss on the interconnection between components for mobile device application, in this study, four switchable bandpass filters based on multicoupled line are proposed for integration of the functions of RF switch and band selection filters. By utilizing the graph transformation technique and insertion loss method, the analysis and synthesis procedure of a fundamental single-pole-single-throw (SPST) switchable bandpass filter (BPF) are much simplified. Then, a compact single-pole-double-throw (SPDT) switchable BPF is proposed. By replacing the quarter-wavelength impedance transformer at the common junction in conventional designs with a J-inverter, the circuit size is largely reduced and the design procedure can be much simplified. In addition, low insertion loss in the on state, good isolation in the off state, and good linearity are obtained. The second design is an extension of the proposed SPDT switchable BPF, in which the output port can be designed as either single-ended or differential ones. The proposed multi-functional circuit can thus effectively integrate the SPDT RF switch, TX/RX BPFs, and balun of a single-band transceiver in one single circuit. In addition, compact circuit size, low insertion loss in the on state, good isolation in the off state; excellent linearity and good balanced performance are achieved. Then, the proposed SPDT switchable diplexer integrates the functions of SPDT RF switch and diplexer, and each signal path can be independently synthesized using the insertion loss method. In addition, by a simple modification to the common resonator, a SPQT switchable quadplexer can be achieved by the connection of two proposed SPDT switchable diplexers. Low loss, compact size, good selectivity, and high linearity are also achieved. All the proposed switchable bandpass filters based on multicoupled line feature compact size and good performances, and they can be good solutions for multi-mode, multi-band RF front end application.
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