Intermodulation distortion characteristics of high-temperature superconducting dual-band bandpass filter

This paper presents the intermodulation distortion (IMD) characteristics of a high-temperature superconducting (HTS) dual-band bandpass filter (DBPF) comprising coplanar-waveguide quarter-wavelength resonator with odd- and even-mode resonant frequencies. The IMD characteristics are one of the most significant factors in order to elucidate the power handling capability (PHC) of HTS filters. The IMD measurements for HTS single-band filters have been reported, while those for HTS-DBPFs have not. This paper introduces the IMD characteristics of the HTS-DBPF when lower band and upper band signals are individually and simultaneously input to each passband, respectively. A 2.0-/3.5-GHz band HTS-DBPF is designed and fabricated as an example for the evaluation of the PHC. Experimental investigations confirm that the proposed HTS-DBPF is effective in achieving both flexible passband control and low IMD generation.