High-Temperature Superconducting Microstrip Line Filter for Mobile Telecommunication

Yoshiki UENO  Kenshi SAITO  Nobuyoshi SAKAKIBARA  Mitsunari OKAZAKI  Masayuki AOKI  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E81-C   No.10   pp.1573-1577
Publication Date: 1998/10/25
Online ISSN: 
DOI: 
Print ISSN: 0916-8516
Type of Manuscript: INVITED PAPER (Special Issue on Low- and High-Temperature Superconductive Electron Devices and Their Applications)
Category: Analog Applications
Keyword: 
high-temperature superconductor,  HTS,  bandpass filter,  filter subsystem,  front-end,  

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Summary: 
Large-area high-temperature superconducting films and damage-free processing techniques have been developed to fabricate low insertion loss and sharp skirt filters for mobile telecommunication. An off-axis-type dc sputtering method was employed to deposit Y-Ba-Cu-O films on both sides of the substrate. The surface resistance of the films was about 0. 35 mΩ(at 70 K and 10 GHz). An 11-pole bandpass receiving filter for the IS-95 telecommunication system was designed and fabricated using 60 mm 50 mm YBCO films on a 0. 5-mm-thick MgO substrate. The passband insertion loss at 70 K was about 0. 1 dB with 0. 1 dB ripple. The third-order intercept point of the filter was 49. 5 dBm. We have assembled the filter and a low-noise amplifier in a dewar with a cryocooler. Ultralow-noise performance (noise figure: 0. 5 dB at 70 K) was presented by the cryogenic filter subsystem.