79GHz Automotive Short Range Radar Sensor based on Single-Chip SiGe-Transceivers

Today automotive short range radar sensors are only available for the 24 GHz band. But in the EU the production of ultra-wideband sensors is limited to 2013 for the 24 GHz band, after 2013 the 79 GHz range must be used. This was the impact to develop a single-chip SiGe RF-transceiver for the 79 GHz-band on Infineon's B7HF200-Process with transition frequencies above 200 GHz. The power spectral density limit of -9 dBm/MHz for the 79 GHz-band is much higher than the -41.3 dBm/MHz limit for 24 GHz. Therefore the built prototype is a FMCW radar and no pulse radar in order to achieve a higher signal-to-noise ratio. The required frequency ramp generation according to the FMCW-principle is realized without a phase locked loop(PLL), but by controlling digitally the tuning voltage of the VCO with help of a D/A-converter. The non-linearity of the VCO tuning law is compensated by measuring the frequency of the divider signal. Two bistatic transceiver variants have been realized: ATRX2 has one transmit and three receive channels, while ATRX3 has two switchable transmitters and two receivers. An RF-board has been designed for each chip, where low-cost patch antennas have been applied, optimized for a short range system. In the following the configuration for both chips is explained and measurement results are presented in order to demonstrate the angle detection capabilities.