An IPD-Based High-Selectivity Bandpass Filter Using Phase Inversion Technique for 5G Millimeter-Wave Application

Aiming at 5G applications, a design strategy for high-selectivity millimeter-wave (mm-wave) bandpass filter (BPF) is presented. The BPF is realized using an inline topology, while effectively combines single-path and multi-path hybrid electric-magnetic coupling mechanisms. By leveraging phase inversion technique, several transmission zeros (TZs) are generated near the passband edges, achieving a record-low rectangular coefficient of 1.88. These TZs can be independently controlled by varying the coupling strength. Implemented in GaAs-based integrated passive device (IPD) technology, the proposed BPF demonstrates a low insertion loss of 1.42 dB at 25 GHz and a 2-octave wide stopband, significantly outperforming conventional cascaded filter designs in both selectivity and anti-interference capability for 5G mm-wave monolithic microwave integrated circuits (MMICs).