PMCW waveform and MIMO technique for a 79 GHz CMOS automotive radar

Automotive radars in the 77-81 GHz band will be widely deployed in the coming years. This paper provides a comparison of the bi-phase modulated continuous wave (PMCW) and linear frequency-modulated continuous wave (FMCW) waveforms for these radars. The comparison covers performance, implementation and other non technical aspects. Multiple Input Multiple Output (MIMO) radars require perfectly orthogonal waveforms on the different transmit antennas, preferably transmitting simultaneously for fast illumination. In this paper, we propose two techniques: Outer code and Range domain, to enable MIMO processing on the PMCW radars. The proposed MIMO techniques are verified with both simulation and lab experiments, on a fully integrated deep-submicron CMOS integrated circuit designed for a 79 GHz PMCW radar. Our analysis shows that, although not widely used in the automotive industry, PMCW radars are advantageous for low cost, high volume single-chip production and excellent performance.