High-Tc Superconducting Planar Filter for Power Handling Capability


IEICE TRANSACTIONS on Electronics   Vol.E79-C    No.9    pp.1228-1232
Publication Date: 1996/09/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section INVITED PAPER (Special Issue on Toward Digital and Analog Applications of Superconductors)
Category: Analog applications
high-Tc superconductor,  filter,  planar filter,  dual-mode resonator,  power handling,  disk resonator,  intermodulation,  

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A high-Tc superconducting filter of the planar structure is proposed for handling higher power signals and for miniaturizing the filter configuration. The filter is designed with a single disk-resonator shared by two degenerate modes to operate as a two-stage bandpass filter. Thereby the proposed filter is expected to possess high power handling capability as a conventional filter with two resonator disks does while the filter configuration is about a half in area compared to the conventional one. The Tchebyscheff type filter with 5.1 GHz center frequency and 2% relative bandwidth was fabricated using a high-Tc superconducting thin film. The passband insertion loss, Lo, was approximately 0.8 dB at 77 K. The low loss performance due to the superconductivity was observed at incident signal levels up to 41.2 dBm (around 15 W) at 20 K, which is limited by the power devices in the measurement setup. In addition, good linearity in the filter responses was confirmed by observing the intermodulation distortion with the two-tone method, which indirectly shows a stable operation with higher power incident signals.