This paper presents an mmWave FMCW radar that can achieve sub-centimeter-scale range resolution at 14GHz chirp-bandwidth while maintaining the radar range beyond 50 meters. To meet the requirements on power efficiency, chirp linearity, and signal-to-noise ratio (SNR), a phase-locked stepped-chirp FMCW radar architecture is introduced. Specifically, a fully integrated radar transceiver comprising an interleaved frequency-segmented phase-locked transmitter and a segmented receiver architecture with high sensitivity is presented. The proposed design addresses the limitations of conventional typeII phase-locked loops (PLLs) in extending the radar bandwidth across multiple sub-bands with identical chirp profiles. Fabricated in a FD-SOI technology, the prototype chip comprises two sub-bands with 14GHz of free-running bandwidth and 10 GHz of phase-locked bandwidth. The system achieves -101.7 phase noise at 1MHz offset, 8dBm of effective isotropic radiated power (EIRP), noise figure (NF), and collective power consumption of transmitter and receiver arrays.