A High-Resolution CMOS Phase Shifter for 79 GHz Imaging Radar and Its Applications

A high-resolution vector-sum phase shifter fabricated using a 28 nm CMOS was developed for a 79 GHz imaging radar. The phase shifter incorporates a process and temperature (P/T) stable in-phase (I)/quadrature-phase (Q) signal generator with a robust matching network and highly linear variable gain amplifiers (VGAs) with a crossing metal-line layout. These techniques contribute to 0.5° phase-setting resolution and a 0.9° root-mean-square (rms) phase error with no calibration process. The developed phase shifters were applied to a 79 GHz imaging radar prototype that consists of eight-channel transmitters and eight-channel receivers. The measurement results show that our prototype can recognize human posture, recognize multiple people, and monitor vital signs.