SHF-Band Compact 3-bit Reconfigurable BPF Employing pHEMT Switched Capacitor Array IC

Abstract

For more efficient use of radio spectrum in 5th generation mobile communication (5G) and beyond, reconfigurable RF circuits that can flexibly change multiple bands are promising. Three-bit reconfigurable bandpass filters (BPFs) have been proposed that employs reconfigurable resonators with branch-line switching structure. However, from the view point of actual implementation, the transmission lines that form branch-lines restrict the circuit size and increase complexity. In this paper, we design a new reconfigurable resonator with a switched capacitor array (SCA) and apply it to 3-bit reconfigurable BPF in SHF band. After analyzing the influence of parasitic capacitance of the RF switches, a 3-bit SCA is designed using 0.5 μm gate pHEMT process including MIM capacitors. Prototype BPF is fabricated for selecting center frequencies from 3.3 to 4.44 GHz. The measured RF characteristic of the prototype is almost same as that of transmission line design, while reducing circuit size remarkably.