HTS filter subsystem for future mobile communication system

• DOI: 10.1007/s11432-008-0085-2
• Publication Date: 2008-06-21T07:31:45Z
• Authors: Tao Zuo; Lan Fang; XinJie Zhao; Xu Zuo; TieGe Zhou; ShaoLin Yan
• Keywords: Electronic filter

A high-temperature superconducting (HTS) filter subsystem consisting of a 10-pole HTS filter with group delay self-equalization, a cryogenic low noise amplifier (LNA), and a cooling device is presented in this paper. The HTS filter has a 0.51% fractional bandwidth at 1955 MHz, simulated in Sonnet, and is fabricated using double-sided Tl2Ba2CaCu2O8 films on 0.5 mm thick LaAlO3 substrate. Measured responses show that the minimum insertion loss of the filter is 0.16 dB, and the out-of-band rejection is better than 75 dB. The slope is 27 dB MHz−1 at the low band edge and 22 dB MHz−1 at the upper band edge. The HTS filter subsystem has a gain of 19.3 dB and a noise figure (NF) of 0.8 dB. Furthermore, the phase distortion of HTS filters is considered, and an efficient design approach for self-equalized HTS filters is proposed.