79 GHz CMOS circuits for phase/amplitude calibration in high-resolution beamforming radar systems

79 GHz fundamental CMOS circuits for phased array calibration are presented to achieve a precise beamforming transmission in high-resolution radar systems. The system study made it clear that an amplitude error up to 1 dB and a phase error within 5° are required in each array branch to prevent a degradation of directional side-lobe suppression by 3 dB. The baseband phase shifter with DC current compensation technique and the 79 GHz gain control amplifier are designed as the phase and amplitude control circuits in a 40 nm CMOS process. The phase shifter achieves fine control resolution of 2.5° with RMS errors of 0.13 dB and 0.72° for amplitude and phase respectively, and the 79 GHz amplifier shows a 14.3 dB gain and a capability of amplitude error compensation. The 79 GHz level detector is designed and it realizes accurate detection performance with less than 1 dB error under process variations.