A fully integrated 77GHz FMCW radar transmitter using a fractional-N frequency synthesizer

A single chip transmitter for automotive FMCW radar application is implemented in 0.18 um SiGe BiCMOS technology. The frequency synthesizer driving a 77 GHz VCO is based on a fractional-N PLL embedding a programmable divider operating at 10 GHz. A 28 bit sigma delta modulator associated to a digital controller enables a versatile generation of FMCW modulation with a resolution of 3 Hz and a linearity of 1%. The measured phase noise is -75 dBc/Hz at 100 kHz offset from a 77 GHz carrier and output power is 18 dBm.