Novel Mixed-Signal Based Short-Range Leakage Canceler for FMCW Radar Transceiver MMICs

The continuous operation of frequency modulated continuous wave (FMCW) radar transceivers leads to permanent leakage from the transmit into the receive path. Besides leakage within FMCW radar systems itself, unwanted reflections from a close object in front of the radar antennas results in socalled short-range (SR) leakage. Specifically the phase noise (PN) contained in the SR leakage causes a severe sensitivity degradation of the radar. In this work, we propose a mixed-signal approach to mitigate the SR leakage, including its contained PN. It makes use of an artificial on-chip target (OCT), whose output signal is modulated on a sinusoidal generated in the digital domain. The concept is based on cross-correlation properties of the residual PN between the OCT and the SR leakage in the intermediate frequency (IF) domain of the transceiver. We prove our analytical investigations with an FMCW radar simulation, wherein almost perfect SR leakage cancelation is achieved.