Dirk Steinbuch

DC-offset compensation of a 77 GHz monostatic FMCW-radar transceiver for automotive application

The DC-offset compensation of a monostatic FMCW-radar transceiver using transmission line (TL) length optimization is proposed. This approach can be implemented on a 77 GHz SiGe MMIC (Monolithic Microwave Integrated Circuit) with no extra costs and does not degrade the sensitivity for immediate targets needed for the stop-and- go functionality of modern ACC (Adaptive Cruise Control) systems. The theory of the DC-offset generation will be discussed and a network analysis of the transceiver will be presented. It is shown that the compensation is possible over a wide range of circuit imperfection values.

A method for the analysis of ramp-inherent linearity distortions in automotive radar applications

Through the use of sensors to provide information about the vehicles surroundings, driver assistance systems increase traffic safety. These sensors must not deliver wrong data due to noise or external distortion. In FMCW Radar systems additionally a highly linear ramp is essential. Hence nonlinear ramps have direct impact on the baseband spectrum. Weak targets could be covered and therefore not detected. This paper describes a method for evaluating the RF ramp linearity, based on analysis of the baseband signal. Therefore the analysis is easier, as the baseband frequency is only a few MHz depending on chirp modulation parameters and target distance. The instantaneous frequency is measured, so that deviations from the ideal slope can be detected immediately. Results are compared with simulations and high frequency measurements with a commercial availably spectrum analyzer which calculates the mean frequency deviation over a high number of ramps.

Development of a mid range automotive radar sensor for future driver assistance systems

Radar sensors are key components of modern driver assistance systems. The application of such systems in urban environments for safety applications is the primary goal of the project “Radar on Chip for Cars” (RoCC). Major outcomes of this project will be presented and discussed in this contribution. These outcomes include the specification of radar sensors for future driver assistance systems, radar concepts, and integration technologies for silicon-germanium (SiGe) MMICs, as well as the development and evaluation of a system demonstrator. A radar architecture utilizing planar antennas and highly integrated components will be proposed and discussed with respect to system specifications. The developed system demonstrator will be evaluated in terms of key parameters such as field of view, distance, and angular separability. Finally, as an outlook a new mid range radar (MRR) will be introduced incorporating several concepts and technologies developed in this project.

Mitigation of weak targets' masking due to nonlinearities in chirp sequence FMCW automotive radar at 77 GHz

The linearity of the transmitted signal in chirp sequence FMCW radar has a direct impact on the radar baseband, which is used for all target detections and safety functionality. In this paper automotive radar sensors are investigated on the linearity of their transmitted frequency slope. Dominant distortions are analyzed. Results show that distortions can cause peak widening, a wide band SNR degradation and masking of weak targets in critical scenarios. This is investigated by simulations and measurements. Also it is shown that many requirements and counter measures are contrary. A system design has to exhibit an optimum trade-off between a high SNR and a high distance resolution.

Defining acceptable phase-modulated nonlinearities in 77 GHz FMCW automotive radar systems

A method to determine the maximum allowable frequency error of a PLL generated FMCW radar slope is presented. Using the side lobe suppression as a metric, the maximum frequency error in a linear FMCW slope is defined based on the used window function. With higher distortion frequency a higher side lobe suppression is required. It is shown that for fast chirp sequence modulation in the absence of any additional counter measures, the minimum allowable frequency error is on the order of a few kHz, which is nearly impossible to be achieved by commercial radar systems.