A 28-nm-CMOS Based 145-GHz FMCW Radar: System, Circuits, and Characterization

This article presents frequency-modulated-continuous-wave (FMCW) radars developed for the detection of vital signs and gestures using two generations of 145-GHz transceivers (TRXs) integrated in 28-nm bulk CMOS. The performance and limitations of high-frequency radars are quantified with a system-level study, and the design and performance of individual circuit blocks are presented in detail. A 145-GHz center frequency and radar operation over an RF bandwidth of 10 GHz yield a displacement responsivity of 2 $\pi $ rad/mm and a windowed range resolution of 30 mm, respectively. Radar operation over a 0.1–7 m range is enabled by an effective-isotropic radiated power of 11.5 dBm and a noise figure of 8 dB. The ICs feature frequency multiplication by 9 in the transmit and receive paths, sub-arrayed dipole antennas, and neutralization of TX–RX leakage via delay control. A single TRX dissipates 500 mW from a 0.9-/1.8-V drive. The use of fast chirps (5–30- $\mu \text{s}$ ) mitigates the effect of 1/ $f$ -noise at the intermediate frequency (IF). Extensive characterization results showcase state-of-the-art performance of the TRXs, while the code-domain multiple-input and multiple-output (MIMO) radars ( $1 \times 4$ and $4 \times 4$ ) built with them demonstrate vital-sign and gesture detections.