Design of superconducting multi-pole miniaturized filters with quasi-spiral resonators for decreasing unwanted cross couplings

作者：Ono S^*; Harada Y; Saito A; Lee J H; Kato T; Uno M; Yoshizawa M; Ohshima S

来源：Physica C-Superconductivity and Its Applications, 2009, 469(15-20): 1649-1652.

DOI：10.1016/j.physc.2009.05.078

• Quasi-spiral resonator (QSR)
• Miniaturized superconducting filter
• Bandpass filter

We designed a 5-GHz miniaturized 8-pole bandpass filter (BPF) using superconducting microstrip quasi-spiral resonators (QSRs) for international mobile telecommunication (IMT)-advanced receiving applications. We used the QSRs with line width and spacing equal to 10 mu m for further miniaturization. and investigated a relationship between the structure of the QSR and the unloaded quality factor (Q(u)). The Q(u) of the optimized QSR of approximately 25,000 was obtained. It was difficult to design a BPF using miniaturized QSRs with high Q(u) because of strong cross couplings between QSRs. The lambda(g)/8-line inserted, inverters were effective in decreasing the unwanted cross couplings. Using these QSR and the lambda(g)/8-line inserted inverters. 8-pole cascaded quadruplet (CQ) BPF was designed. We found that it was possible to design a miniaturized BPF with high Q(u).

• 出版日期2009-10