FPGA controlled DDS based frequency sweep generation of high linearity for FMCW radar systems

Two significant requirements in an FMCW radar system are linearity and low phase noise. Especially in range detection applications the achievable accuracy directly depends on the linearity of the modulated radar signal. In general PLL based systems with digital generated reference signals are used to meet this requirement. In this paper an FPGA controlled DDS based signal generator for highly linear frequency sweeps is introduced. Measurements demonstrate the approached linearity of an FMCW radar in the K-band with 1 GHz bandwidth and a sweep time of 50 μs. In addition signal processing aspects for measurements and evaluation are derived.