IPD Millimeter-Wave Bandpass Filter Chip Based on Stepped-Impedance Coupled-Line Dual-Mode Resonator for 5G Application

A novel stepped-impedance coupled-line dual-mode resonator (SICLDMR) is presented and analyzed in this brief. The resonator is a closed ring structure, constructed by two coupled lines with different impedances. The even- and odd-mode resonance frequencies of this SICLDMR are created due to the different effective dielectric constants of the two modes. Based on the proposed resonator, a simple bandpass filter (BPF) is designed by adding two symmetric open-stub feeding structures. For demonstration, a narrowband BPF operating at 35 GHz is simulated, fabricated by using the 100- ${\mu }\text{m}$ -thick-GaAs integrated passive device (IPD) technology. And the measured results show that the BPF with a good fractional bandwidth of 13% realizes a low insertion loss of 0.74 dB, sharp roll-off skirt of passband, and wide stopband rejection. The advantages of the proposed IPD BPF indicate that it has a promising application prospect in 5G millimeter-wave systems.