A UWB Impulse-Radio Timed-Array Radar With Time-Shifted Direct-Sampling Architecture in 0.18- $\mu{\rm m}$ CMOS

This paper presents a ultra-wideband (UWB) impulse radio timed-array radar utilizing time-shifted direct-sampling architecture. Time shift between the sampling time of the transmitter and the receiver determines the time of arrival (TOA), and a four-element timed antenna array enables beamforming. The different time shifts among the channels at the receiver determine the object´s direction of arrival (DOA). Transmitter channels have different shifts, as well, to enhance spatial selectivity. The direct-sampling receiver reconstructs the scattered waveform in the digital domain, which provides full freedom to the backend digital signal processing. The on-chip digital-to-time converter (DTC) provides all the necessary timing with a fine resolution and wide range. The proposed architecture has a range and azimuth resolution of 0.75 cm and 3 degrees, respectively. The transmitter is capable of synthesizing a variety of pulses within 800 ps at a sampling rate of 10 GS/s. The receiver has an equivalent sampling frequency of 20 GS/s while supporting the RF bandwidth from 2 to 4 GHz. The proposed designs were fabricated in a 0.18- μm standard CMOS technology with a die size of 5.4×3.3 mm² and 5.4×5.8 mm² for the transmitter and the receiver, respectively.