SHF-Band 3-bit Reconfigurable BPF Employing pHEMT Switch Arrays for 5G Multiband Operation

For the efficient use of frequency spectrum under multi-band operation in 5th generation mobile communication (5G), RF circuits that can flexibly switch multiple bands are important. Three-bit reconfigurable bandpass filters (BPF) have been proposed that can choose one of eight center frequencies in UHF or SHF bands. However, the RF switches employed for the frequency switching have been treated as ideal component and not studied in detail. In this paper, we focus on the FET switches in the reconfigurable BPF for SHF band and analyze the influence of their parasitic elements on the performance of BPF. In order to reduce insertion loss of the BPF, a new gate width design method for RF switch array (SWA) is proposed. A 3-bit RF SWA is fabricated using 0.5 μm gate pHEMT process and installed in the prototype BPF with passband center frequency changeable from 3.5 to 4.64 GHz. The measured RF characteristic of the prototype is close to the result of circuit simulation.