A Compact 6-bit Sub-GHz Phase Shifter With Inductor-Shared Topology and Equivalent Bandpass Network

This letter presents a compact 6-bit digitally controlled phase shifter achieving 86% relative bandwidth (0.2–0.5GHz) for sub-GHz applications. Three innovations address wideband low-frequency challenges: fine phase shifters (5.625° and 11.25°) utilize an inductor-shared topology, reducing transistors by 50% and eliminating one inductor; coarse phase shifters (22.5°–180°) employ an equivalent bandpass (EBP) network via cascaded high-pass (HP) and low-pass (LP) sections to suppress amplitude variation; and the 180° unit implements main/auxiliary inductor cotuning for precise phase-amplitude control. Fabricated in 0.15-$\mu $m GaAs with a$4.9\times 3.0$-mm2area, the design demonstrates root-mean-square (rms) phase error13dB, and P${}_{\mathrm {1{\,}dB}} \gt 21.5$dBm. To the best of our knowledge, this represents the first reported sub-GHz phase shifter achieving >80% relative bandwidth.