自均衡相位特性的超导滤波器小型化设计

摘要

提出了一种具有多个传输零点的高温超导滤波器小型化设计方法.该滤波器由十个慢波交叉指结构谐振器和三个自均衡CQ跨线结构组成,其中一个CQ结构通过产生一对实轴上的传输零点实现相位均衡,另外两个CQ结构通过产生两对虚轴上的传输零点实现滤波器的高频率选择性.滤波器中心频率为1,720MHz,带宽为10MHz,通带外陡峭度为40dB/MHz,通带内回波损耗为23dB,且在60％的通带内具有平坦的群时延响应.在MgO衬底上采用DBCO高温超导薄膜制作十阶超导滤波器,并在77K温度下进行测试,最终得到了良好的带外抑制性能和平坦的群时延特性.测试结果与仿真结果基本一致,说明所提出的设计方法是有效的.%This paper presented the design of a compact high temperature superconducting (HTS) filter with group delay equalization.The filter exhibited excellent frequency response implemented with three quadruplet coupling structures realized by four microstrip resonators.One quadruplet was applied to generate one pair of transmission zeros on real axis for phase equalization.The other two were applied to generate two pairs of transmission zeros on imaginary axis for high selectivity.The filter was designed at 1720 MHz with a bandwidth of 10 MHz.The full-wave EM simulation was performed to design the filter.And the simulated results were in good agreement with the theoretical response.The filter was fabricated on a MgO wafer with double-sided DBCO films.The RF measurement was performed at 72 K.And after tuning,the filter shows good performance in both transmission response and group delay.The good agreement between the measurement and the simulation demonstrates the validity of the reported method.