Fast 77 GHz chirps with direct digital synthesis and phase locked loop

In automotive radar systems in the 77 GHz range, integrated VCOs based on silicon germanium become more and more state-of-the-art. In the application of a frequency modulated continuous wave radar, a precise frequency modulation is a prerequisite for accurate measurements. In this paper, we investigate different topologies for the linearization of high frequency sweeps based on a direct digital synthesizer and an integer-N-PLL. The obtained results are viewed in terms of the phase deviation from the theoretical course.