56 GHz bandwidth FMCW radar sensor with on-chip antennas in SiGe BiCMOS

This paper presents the design and characterization of an ultra wideband FMCW radar sensor. The radar frontend consists of transmitter and receiver chips in SiGe BiCMOS technology with on-chip antennas. Both chips share the same reference chirp signal, multiplied 8 times to the desired operation band. The radar frontend demonstrates a bandwidth of 56.8 GHz from 104.4 GHz to 161.2 GHz, which corresponds to a theoretical range resolution of 2.6mm. The on-chip antenna occupies only 1.2 × 0.9mm² without any post-micromachining and exhibits a measured gain above 4 dBi for more than 28 GHz of bandwidth. The sensor covers a bandwidth from 105 to 160 GHz with about 10 dB Tx-to-Rx gain fluctuation and less than 39 dBc harmonic power. The radar sensor was tested with FMCW chirps for different scenarios, showing a range resolution of approximately 5 mm.