A Novel Compact HTS Interdigital Bandpass Filter Using CPW Quarter-Wavelength Resonators

Zhewang MA  Tamio KAWAGUCHI  Yoshio KOBAYASHI  Daisuke KOIZUMI  Kei SATOH  Shoichi NARAHASHI  

IEICE TRANSACTIONS on Electronics   Vol.E89-C   No.2   pp.140-144
Publication Date: 2006/02/01
Online ISSN: 1745-1353
DOI: 10.1093/ietele/e89-c.2.140
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Superconducting High-frequency Devices)
high temperature superconductor,  coplanar waveguide,  bandpass filter,  

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A novel high temperature superconducting interdigital bandpass filter is proposed by using coplanar waveguide quarter-wavelength resonators. The CPW resonators are arranged in parallel, and consequently the filter becomes very compact. The filter is a 5-pole Chebyshev BPF with a midband frequency of 5.0 GHz and an equal-ripple fractional bandwidth of 3.2%. It is fabricated using a YBCO film deposited on an MgO substrate. The measured filtering characteristics agree well with EM simulations and show a low insertion loss in spite of the small size of the filter.