A 28-GHz Switched-Filter Phase Shifter with Fine Phase-Tuning Capability Using Back-Gate Biasing in 22-nm FD-SOI CMOS

This paper introduces a phase shifter based on switched filters for mm-wave 5G MIMO transmitters. It is realized in 22 nm FD-SOI CMOS and exploits the use of back-gate biasing. The new approach features strong tolerance to process, voltage and temperature (PVT) variations and thus can maintain low phase error with fine phase tuning capability supporting a large bandwidth. Measurement results show that the 4-bit phase shifter achieves 3.5° rms phase error at 28 GHz. The proposed phase shifter can maintain <5° of the worst-case rms phase error when operating across 24 to 29.5 GHz resulting in 20.56% fractional bandwidth which is the largest among the published switched-filter phase shifters to date.