Packaged 5G Filter With Miniaturization and Wide Stopband Based on Shielded Stripline Resonator

Abstract

The study presents a self-packaged bandpass filter (BPF) with miniaturization and wide stopband based on shielded stripline resonators using a mixed coupling scheme. First, the miniaturized effect and the field distribution at fundamental and spurious modes of a single resonator are analyzed. Then, a mixed coupling scheme is applied to two coupled resonators for spurious passband suppression to achieve wide stopband, which is verified by the second-order BPF response. Finally, shielded stripline resonators with a mixed coupling scheme are further applied to the design of the fourth-order 5G N78 band BPF. The final self-packaged fourth-order BPF achieves an extremely small volume of $0.144\times 0.139\times 0.025\lambda 3$ g, whose stopband is extended up to 5.11f0 with a rejection level better than 20 dB or 3.37f0 with a rejection better than 50 dB.