76–81-GHz CMOS Transmitter With a Phase-Locked-Loop-Based Multichirp Modulator for Automotive Radar

This paper presents the design of a linear frequency-modulated continuous-wave (FMCW) radar transmitter (TX) for automotive radar applications. The TX has a wide operating range from 76 to 81 GHz by employing a frequency-doubling architecture using an LC voltage-controlled oscillator operating at 38-40.5 GHz and a differential frequency doubler using a single transformer. A chirp generator is integrated into the TX, which provides various frequency chirp profiles with programmable chirp slope and sweep duration. The proposed CMOS FMCW TX can be applied to various modulation algorithms for multiple target detection and the avoidance of ghost targets. The TX is implemented using 65-nm CMOS technology. The chip size is 1.48 × 1.85 mm2. The measurement results shows a 76-81-GHz frequency range and 3-dBm output power while dissipating 320 mW. The phase-noise density of the TX is -83.33 dBm/Hz at an offset frequency of 1 MHz when the output frequency is 77 GHz.