Design of Triple-Mode Bandpass Filter Using Improved Ring Resonator

This work presents a novel triple-mode ring bandpass filter with capacitive loading stubs for 5G wireless communication application. Through proper design of input/output coupling configuration, a bandpass filter (BPF) response with three modes and two transmission zeros can obtain. A pair of transmission zeros are close to the passband, improving the out of band selectivity. The proposed BPF operating at 3.5GHz is designed, fabricated and measured. The measured results are in good agreement with the simulated values.