A 4-bit Bidirectional Phase Shifter for 3GHz S-Band Applications

This paper proposes a transmission-line based bidirectional reflection-type phase shifter for the 2.5 to 3.2 GHz frequency band. Open and short reflective loads are used to double the available phase shift and reduce insertion loss. The transmission line is implemented using inductors and MOS switches in a 65 nm RF CMOS process. This work achieves a total phase shift of 180° with phase resolution of 22.5° at 2.85 GHz and rms error of 1.2°. The insertion loss of the phase shifter is 5.7 dB and the loss variation is less than 0.3 dB.