Abstract: A time division duplexed (TDD) frequency modulation continuous wave (FMCW) radar system includes P transmitter circuit chains and M receiver circuit chains. The P transmitter circuit chains are used to transmit a plurality of FMCW signals. A pth transmitter circuit chain is coupled to a single pole Op throw (SPQPT) radio frequency (RF) switch, the SPOT RF switch is coupled to Op antennas, Qp and P are positive integers, and p is a positive integer not larger than P. The M receiver circuit chains are used to receive a plurality of reflected FMCW signals. An mth receiver circuit chain is coupled to a single pole Nm throw (SPNmT) radio frequency (RF) switch, the SPNmT RF switch is coupled to Nm antennas, Nm and M are positive integers, and m is a positive integer not larger than M.

Abstract: In a radar sensor, a transmitting antenna is configured to radiate a transmitted RF signal, a receiving antenna is configured to receive a reflected RF signal from a target, and a frontend circuit is configured to calculate the distance between the target and the radar sensor by measuring the frequency shift between the transmitted RF signal and the reflected RF signal. The frontend circuit includes a crystal-less signal synthesizer configured to generate the transmitted RF signal without using a crystal, and a mixer configured to provide an IF-band signal associated with the frequency shift between the transmitted RF signal and the reflected RF signal by mixing the reflected RF signal and the transmitted RF signal.