A 28-GHz Low Insertion Loss Variation 4-Bit Phase Shifter

This paper presents a 28 GHz low insertion loss variation 4-bit phase shifter which cover 360° phase. The phase shifter is implemented using 28-nm CMOS process. The phase shifter is based on switched delay type phase shifter topology. In order to reduce the insertion loss imbalance, it is designed so that resonance admittance that caused by shunt inductor and parasitic capacitance of off state shunt switching transistor is the same as on resistance of shunt switching transistor. The Fabricated 4-bit phase shifter has 10.1° RMS phase error and 0.78 dB RMS insertion loss at the center frequency. The lowest RMS phase error is 6.4° at 25 GHz and the lowest RMS insertion loss error is 0.18 dB at 30 GHz. The measured insertion loss is 11.7 ± 2.4dB from 28 to 31 GHz over all 16 states.