A D-band Calibration-Free Passive 360° Phase Shifter With 1.2°RMS Phase Error in 45 nm RFSOI

This paper presents a new concept of passive phase shifters based on manipulating propagation delay through two parallel transmission lines periodically connected via digitally controlled switch networks. The proposed approach enables precise phase control and flat amplitude response across different phase settings. The prototype IC is fabricated in a 45 nm RFSOI process and occupies only 0.033 mm
²
. The phase control operates with 11.25°steps over 360° at 140 GHz while maintaining an RMS phase error of 1.2°. The insertion loss is 11.5 dB with < ±0.8 dB variation. Among published D-band phase shifters, this work achieves the lowest RMS phase error and reports bi-directional phase control over 360° and calibration-free operation.