Miniaturized IPD bandpass filter design with high out-of-band rejection for 5G applications

This letter proposes a miniaturized integrated passive device (IPD) bandpass filter (BPF) design with high out-of-band rejection for 5G applications. In this design, a novel topology based on the modified high-pass filter cascaded with the modified low-pass filter is introduced with two pairs of transmission zeros (TZs) at high and low frequencies. In addition, one grounded capacitor at the input is added to improve the suppression at high frequency end. The proposed BPF design is fabricated on silicon substrate. The measured insertion loss is around 3 dB and the return loss is <16 dB in the whole frequency range from 3.3 to 4.2 GHz for 5G applications. This proposed BPF achieves more than 20 dB sideband suppression at both stop bands from DC to 2.69 GHz and from 5.3 to 14 GHz. The fabricated device has a size of only 1 x 0.7 x 0.2 mm.