A 3‐Bit Low‐Phase‐Error 360° Terahertz Phase‐Shifting Chip Using Branch Impedance Reconfiguration

Abstract

ABSTRACT For terahertz devices, realizing full 360° phase shifting while maintaining low phase error, low insertion loss, and low amplitude fluctuation remains a formidable challenge. Owing to the short wavelength of terahertz waves, pronounced parasitic effects in traditional circuits cause undesirable performance degradation during phase shifting. This work proposes a 360° low‐phase‐error phase‐shifting solution combining an L‐shaped in‐line probe with 180° and 45° phase‐shifting units. The L‐shaped in‐line probe enables a low‐loss waveguide‐microstrip transition for large‐area substrates. Schottky barrier diodes (SBDs) are employed for impedance reconfiguration of the reflective branches in one 180° phase‐shifting unit and the parallel branches in three 45° phase‐shifting units. Furthermore, incorporating matching lines to decouple inter‐unit interference can reduce phase error, insertion loss, and amplitude fluctuation. Ultimately, utilizing coded voltage control enables us to achieve a 3‐bit (45° precision) 360° phase shift featuring insertion loss less than 12.6 dB and amplitude fluctuation less than 3 dB at 224.5 GHz. The superior performance in terms of low phase error and amplitude consistency makes this chip an ideal component for terahertz applications.