Untersuchung eines Systemkonzeptes für KFZ-Radarsensoren auf der Basis Monolithisch integrierter Hochfrequenzmodule (English shop)

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Electronic assistance systems which support the driver in various situations are increa-
singly applied in automobiles. For the sensing of the surrounding of a car different
sensor types are deployed, like ultrasonic, video, infrared and radar. Radar sensors
offer several advantages compared to other principles. They enable the direct and pre-
cise measurement of range and speed, and the sensors are to a great extent independent
of environmental conditions like rain or fog. The main automotive application of radar
sensors today is the adaptive cruise control which is based on long range sensors with
transmit frequencies in the range of 76 – 77 GHz. Furthermore, applications requiring
additional short range sensors are emerging, as for example pre-crash detection. Trans-
mit frequencies of the short range sensors are currently around 24 GHz, but in the long
term the frequency band from 77 – 81 GHz will be used. This allows a size reduction
and yields technological synergies between short and long range sensors.
This thesis examines a new type of radar sensor architecture comprising an array
of transceiver modules, which is targeted at frequencies in the MMW-range around
77 GHz or above. The basic idea underlying the proposed architecture is the monolithic
integration of complete transceivers including the primary antenna element. By the
monolithic integration the high-frequency signal paths are bounded to the ICs and no
MMW connections are going off-chip. This reduces line losses and the assembly of the
RF-frontend is simplified.
The properties of the transceiver array architecture in conjunction with electronic
beam steering are investigated. The proposed architecture offers an increased flexibility
compared to existing concepts. Due to the degrees of freedom offered by the availability
of spatially distributed signal sources, different array characteristics can be imposed
by adopting the transmit signals. An FMCW-modulation scheme and accompanying
signal processing is described, which allows the direct and unambiguous calculation
of range and velocity in multiple target situations, as well as a synthetic doubling of
the physical aperture without the need for phase synchronization of the signal sources.
The analytical results are verified by an experimental radar sensor comprising eight
parallel transceiver channels in a hybrid assembly in the frequency range 76 – 77 GHz.
Results of static and dynamic measurements are presented which show the potential
of the concept for high resolution radar sensors.
Furthermore, the feasibility of the monolithic integration of the transceiver modules
at MMW-frequencies is demonstrated by the realization of key transceiver components
in different SiGe-technologies. The design and experimental results of fundamental- and
push-push-oscillators, as well as an antenna system with a monolithically integrated
primary resonator for frequencies around 122 GHz are presented.