A -TDC-Based Beamforming Method for Vital Sign Detection Radar Systems

This brief describes a time-to-digital converter (TDC)-based digital-intensive beamforming method that is insensitive to analog delay mismatches. For vital sign detection, the proposed architecture can perform either vector summation (beamforming) or scalar summation (beamsumming) in the digital domain by simply weighting or removing the direct-current term for each channel, thus not requiring analog delay circuits. A prototype four-channel radar receiver that utilizes a digital phase tracking circuit and a 1-bit delta-sigma TDC is implemented in the 0.18-μm CMOS. The digital-intensive receiver consumes 33.2 mW/channel from a 1.8-V supply and successfully demonstrates spatial selectivity and signal-to-noise-ratio enhancement.