LAUSR

In this brief, a novel ring type wideband bandpass filter with multi-reflection zeros (RZs) is presented. The proposed topology consists of two signal electrical paths between two output ports, where there are three $\lambda $ /4 parallel-coupled line sections to be cascaded in each path. By using the proposed approach, 7 equal-ripple performance with adjustable group delay can be realized in the passband. Considering further simplification in design, several parallel-coupled line sections can be substituted by TLs, thus attaining 5 simplified topologies with the same filtering response. Compared with the former works, the proposed work not only provides 8 RZs in the realized passband with equal-ripple and controllable group delay, but also achieves simple circuit and easy fabrication. For verification, one prototype circuit is in final fabricated, and the measured frequency response have well verified the proposed design approach.