A Calibration-free FMCW Synthesizer for Automotive Radar with Fast Frequency Modulation and Reset Ability

A fully integrated 18.6-20.4 GHz FMCW synthesizer for automotive radar applications is presented. The design employs a dual-loop PLL with feedback down-conversion and a transformer-based VCO to address the trade-off between phase noise and maximal chirp slope. The synthesizer achieves −108.4 dBc/Hz phase noise at 1 MHz offset and supports chirp slopes of up to 100 MHz/µs with an RMS frequency error of 92 kHz, without calibration or predistortion. A dynamic chargepump current scaling mechanism enables boosting the loopbandwidth between chirps, achieving a 3.1 µs retrace time for a 1.75 GHz sweep.