Design of Dual-Band SHF BPF with Lower Band Reconfigurability and Direct Parallel-Connected Configuration

Yuki KADA  Yasushi YAMAO  

IEICE TRANSACTIONS on Electronics   Vol.E101-C   No.10   pp.775-783
Publication Date: 2018/10/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E101.C.775
Type of Manuscript: Special Section PAPER (Special Section on Microwave and Millimeter-Wave Technologies)
reconfigurable circuit,  bandpass filter,  coupling circuit,  dual-band,  parallel connection,  

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For more flexible and efficient use of radio spectrum, reconfigurable RF devices have important roles in the future wireless systems. In 5G mobile communications, concurrent multi-band operation using new SHF bands is considered. This paper presents a new configuration of dual-band SHF BPF consisting of a low SHF three-bit reconfigurable BPF and a high SHF BPF. The proposed dual-band BPF employs direct parallel connection without additional divider/combiner to reduce circuit elements and simplify the BPF. In order to obtain a good isolation between two passbands while achieving a wide center frequency range in the low SHF BPF, input/output impedances and external Qs of BPFs are analyzed and feedbacked to the design. A high SHF BPF design method with tapped transmission line resonators and lumped-element coupling is also presented to make the BPF compact. Two types of prototypes; all inductor-coupled dual-band BPF and C-L-C coupled dual-band BPF were designed and fabricated. Both prototypes have low SHF reconfigurable center frequency range from 3.5 to 5 GHz as well as high SHF center frequency of 8.5 GHz with insertion loss below 2.0 dB.