A Compact Low Loss Onchip Bandpass Filter For 5G Radio Front End Using Integrated Passive Device Technology

A compact very low loss onchip bandpass filter which suits the 5G radio frequency front end (RFFE) filtering requirements, is reported here. The proposed filter is modeled using 0.18 μm CMOS Silicon substrate IPD technology. A series LC resonant onchip BPF structure is designed and simulated by combining a passive multilayer (ML) spiral inductor and a planar spiral capacitor in High Frequency Structural Simulator (HFSS) at component level. The filter showed a quality factor (Q) value of 7.3125 and a fractional bandwidth of 13% (<; 20%). It had exhibited very good insertion loss of -0.415 dB and also excellent return loss of -42.9 dB, at a self-resonant (SRF) frequency of 3.5 GHz. The physical dimensions of the Inductor, Capacitor and bandpass filter are 340×240 μm², 280×240 μm² and 480×240 μm² respectively. It had demonstrated with an excellent loss along with a narrow passband characteristics, still occupying very small onchip area. Hence, this compact resonator filter definitely suits the 5G front end filter applications. We simulated this filter by focusing around 3.5 GHz, as this spectral band is used in 4G and also being actively considered for several 5G trials and installations across several countries.