Compact Band Pass Filter Design for 5G N77 Using GaAs Integrated Passive Device Technology

In this paper, a 5G N77 bandpass filter (BPF) using GaAs integrated passive device (IPD) technology is proposed. This BPF is designed based on LC series-parallel resonators to achieve low loss and wide passband. By carefully tuning the values of the inductance and capacitance in LC shunt resonators, it can obtain multiple transmission zeros (TZs) in upper and lower stop bands. On this basis, three-dimensional BPF elements are build up. By optimizing the structures of spiral inductors, their Q values can be effectively improved. In addition, the overall circuit insertion loss (IL) can be reduced in the passband. Furthermore, the BPF layout with Ground-Signal-Ground (GSG) probe test ports has been implemented. The total size is 1.69 × 1.72 × 0.1 mm³. The Results show the BPF has a passband of 3.24-4.17 GHz with return loss (RL) better than 15 dB. The IL is less than 2.6 dB and the 3-dB fractional bandwidth reaches 30.4%. The attenuation is greater than 29 and 30 dB in DC-2.7 GHz and 5.1-15.25 GHz respectively with sound frequency cutoff characteristics. In particular, the attenuation is greater than 40 dB from 5.65 to 13.95 GHz, providing good broadband signal suppression.