A high-temperature superconducting filter for future mobile telecommunication systems

Abstract

This paper presents a narrow-band high-temperature superconducting bandpass filter on a sapphire substrate applicable to future mobile communications systems. The design and simulation of a ten-pole quasi-elliptic function filter implemented using a cascaded quadruplet trisection coupling topology is discussed. The filter is designed to have a 10-MHz passband in the Universal Mobile Telecommunications System base-station receive band. The filter substrate was a sapphire wafer measuring 47 mm 17 mm 43 mm, which had a double-sided thin-film coating of Yba 2 Cu 3 O 7 . The filter displayed a minimum insertion loss of 0.2 dB in the passband and a return loss better than ( 12 dB preliminary) over the passband. A high performance out-of-band rejection associated with a quasi-elliptic filter function was also recorded.

Design of special asymmetric cul-de-sac unit configuration high temperature superconductor filter with multi-pair of transmission zeros

“…With both the maturity of the preparation technology of HTS film and improvement of refrigeration level, the application of HTS receiver front-end in mobile communication base stations is becoming prevalent [1][2][3][4][5][6][7][8][9]. Effective improvement of the out-of-band suppression in the bandpass filters can be achieved by introducing transmission zeros (TZs) on the imaginary axis on complex plane and notches [1][2][3][4][5][10][11][12][13][14][15]. Cross coupling is one of the most widely-used methods to introduce TZs in HTS filters.…”

“…There are various cross-coupled folded configurations such as the ones shown in figure 1. These are 8-pole filters with an inline topology, Pfitzenmaier, cascaded triplet (CT) [2,11], cascaded quadruplet (CQ) [16] and parallel-connected configurations [17]. This paper innovatively introduces a special asymmetric cul-de-sac unit (SACU) to design the generalized Chebyshev function bandpass filter.…”

“…This paper innovatively introduces a special asymmetric cul-de-sac unit (SACU) to design the generalized Chebyshev function bandpass filter. This configuration allows the introduction of multiple TZs but is different from classic CT and CQ structures which have been usually used [1,2,8,10]. Such a filter can be composed of several SACUs each introducing a pair of TZs on the imaginary axis.…”