The Demonstration of Through Superconducting Substrate Via (TSSV) and Its Application to Transversal Cross-Coupling HTS Filter Design

This article proposes and verifies the through superconducting substrate via (TSSV) technology for high-temperature superconducting (HTS) filters for the first time, which can be used to achieve vertical interconnection of superconducting substrates (YBCO/magnesium oxide (MgO)], advancing the design and manufacturing of HTS filters from 2-D plane to 3-D integration. The vertical interconnection between the top and bottom layers of the superconducting coplanar waveguide (CPW) lines is realized using TSSV. A dual-mode resonator based on TSSV is constructed, and the characteristic plane method (CPM) is proposed to uniquely distinguish multiple odd- and even-mode frequencies. A systematic study of the transverse cross-coupling structure is presented, through formula derivation, the influence of cross-coupling is separated from the total coupling, allowing for a clear analysis of its impact on the filter response. To validate the proposed methods, two- and four-stage transversal cross-coupling HTS filters are designed using TSSV. The measured results show excellent agreement with the design specifications.