SiGe Circuits for Spread Spectrum Automotive Radar

This paper presents circuits in SiGe bipolar technology for spread spectrum automotive radar applications in the band from 77 to 81 GHz. They cover the transmit and receive paths. The transmitter integrates a voltage controlled oscillator, a prescaler by 64, a 10 bit linear feedback shift register (LFSR), and a biphase modulator. The system has been optimized in order to achieve a range resolution less than 12 cm and an unambiguous range of 124 m. The quadrature receiver frontend consists of a single-ended low-noise amplifier (LNA), balanced-to-unbalanced converters, two fully differential direct-conversion mixers, LO buffer amplifiers, and a branchline coupler for I/Q generation. The presented systems show that millimeter-wave circuits in SiGe technology can achieve high integration levels along with high performance. They are well suited for application in spread spectrum automotive radar systems.