Multi-channel Low-noise receiver and transmitter for 76-81 GHz automotive radar systems in 65 nm CMOS

This paper presents the design and characteristics of a receiver and a transmitter in 65-nm CMOS technology for automotive radar systems covering dual radar bands of 76 GHz and 79 GHz. The receiver has a 4-channel fully differential configuration for DBF systems. A unit receiver achieves a single-side band noise figure of 12 dB at an IF range from 1 to 200 kHz using a low 1/f-noise double-balanced resistive mixer and a low-noise differential amplifier. Using an on-chip multi-channel DAC, the receiver maintains a constant conversion gain with varying temperature by means of the fine control of gate bias voltages. The transmitter has a 2-channel configuration for multi-transmitting mode and includes a frequency PLL synthesizer. The transmitter achieves a phase noise of -84 dBc/Hz at a 100 kHz offset using an XOR-type phase detector and a 49-MHz reference. Due to the wider frequency circuit operation of frequency dividers and a VCO, the frequency synthesizer in the transmitter achieves a 76-81 GHz frequency range operation. We demonstrate 5-GHz band width FMCW and 10-μs fast-FM signal generation using the transmitter.