A 77 GHz FMCW radar transmitter with reconfigurable power amplifier in 65 nm CMOS

A frequency modulated continuous-wave (FMCW) radar transmitter in 65 nm CMOS is presented. The transmitter consists of one FMCW signal generator, one reconfigurable power amplifier and bias circuits. FMCW chirp signal comes from a sigma-delta modulated fractional-N phase-locked loop (PLL) with an integrated digital triangle-wave generator to control the output division-ratio of the sigma-delta modulator. A four-way power combining power amplifier is employed to improve the output power with a reconfigurable output power to satisfy different detection distance requirements. The measured results show that the chirp bandwidth achieves 2 GHz, from 76 GHz to 78 GHz, and the power amplifier achieves 13.1 dBm output P1dB with 8.1% PAE. The power amplifier and FMCW signal generator consume 228 mW and 56 mW power, respectively, with a 1.0 V power supply. The core die area is only 2.6×0.88 mm2.