A miniaturized 28 GHz 4-bit phase shifter in 65 nm LP CMOS for multi-channel 5-G radios

A 65 nm LP CMOS 4-bit phase shifter for 28 GHz 5G applications is presented. Sharing inductor footprints and using a switched inductor allow ~50% of layout size reduction, compared to conventional design. On-wafer testing shows that the fabricated phase shifter exhibits 14.3 dB average insertion loss over the 27.5–28.35 GHz band. Measured input and output return losses are >7.2 dB. Measured RMS phase and gain error are 9.4° and 2.7 dB at 28 GHz, respectively. Measured input P_1dB is >11 dBm. The chip area excluding pads is 0.067 mm², ×2 more compact than previous Ka-band phase shifters, to the best of authors' knowledge. The presented phase shifter allows low-cost IC implementation of multi-channel 5G transceivers.