A Broadband Reflection-Type Phase Shifter Achieving Uniform Phase and Amplitude Response across 27 to 31 GHz

This paper demonstrates a broadband reflection-type phase shifter (RTPS) for millimeter-wave phased-array applications. Implemented in 45-nm SOI CMOS, the proposed bidirectional RTPS provides a full 360 deg. phase-shift with a five-bit phase resolution. It incorporates an additional series inductor/varactor resonator to a Pi-based varactor/inductor/varactor network to broaden both the phase-shift range and bandwidth and to allow a single set of voltages to control the RTPS response over the full 27 to 31 GHz bandwidth (13.8% fractional bandwidth). A method is proposed to select these control voltages under an intended insertion-loss constraint to minimize the average root-mean squared (RMS) phase error across the entire band. Across the full band, the RTPS achieves an RMS phase error less than 3.8 deg, insertion loss of 8.5 to 10 dB, and RMS gain error less than 0.5 dB across the band.