Third-order filtering crossover using dual-mode resonator for high-isolated channels

This paper proposes a high-selective crossover with a third-order filtering characteristic, high passband isolation, and multiple controllable transmission zeros based on a coupled topology using single- and dual-mode resonators. By virtue of the odd- and even-mode feature of the stub-loaded dual-mode ring resonator, not only can the two resonant modes for different passbands be relatively independently controlled, but also better isolation can be achieved. With a single-mode resonator and stub-loaded dual-mode resonant coupling topology, the resultant crossover can perform third-order filtering performance in two distinct passbands/channels and generate several transmission zeros outside the desired bands to improve the isolation between the passbands. Experimental results demonstrate that, compared with conventional works, the filtering order of the proposed crossover is promoted and its passband isolation can be significantly improved by about 8 dB. The proposed work may facilitate its widespread applications in high-performance multichannel integrated microwave systems for avoiding interference between multiple intersecting signal paths. This paper proposes a high-selective crossover with a third-order filtering characteristic, high passband isolation, and multiple controllable transmission zeros based on a coupled topology using single- and dual-mode resonators. Compared with conventional works, the filtering order of the proposed crossover is promoted, and its passband isolation can be significantly improved. The proposed work may facilitate its widespread applications in high-performance multichannel integrated microwave systems.image