Differential HTS Bandpass Filters Based on Coplanar Stripline

This paper introduces two implementation methods for high-temperature superconducting (HTS) balanced bandpass filters using slot-line resonators (SLSR) and coplanar strip lines (CPS). The inherent common-mode (CM) suppression characteristics of both slot-line and CPS contribute to the excellent common-mode rejection and superior differential-mode (DM) transmission properties exhibited by these two filters. The application of CPS enables effective control of the overall filter size. The proposed filters, designed as five-order and four-order filters using NaAlO
2
and Rogers 6010LM substrates, respectively, achieve center frequencies of 6.25 GHz and 3.5 GHz, with fractional bandwidths of 48% and 40%.