Thumbtack-Sized Distance and Motion Sensor Serves as Pocket Radar

Today’s parking assistant systems enable drivers to safely park their cars even in the narrowest of gaps. Such sophisticated parking aids – as well as manufacturing robots – that require millimeter-precision control rely on precise all-around radar distance measurement. Together with the Karlsruhe Institute of Technology (KIT), the SUCCESS Consortium now has succeeded in integrating the necessary radar technology into millimeter-sized chip housings.

The sensor sends and receives electromagnetic waves having a frequency of 122 GHz, which corresponds to a wavelength of approximately two-and-a-half millimeters. From the runtime of the waves, the distance to an object that is several meters away is calculated with an accuracy of up to less than one millimeter. In addition, the velocity of the respective object can be measured via the Doppler effect. The sensor measures only 8 x 8 millimeters, but contains all the necessary radio-frequency components. The output signals thus are signals of low frequency that can be processed further by means of standard electronic systems.

Besides vehicle environment detection and control of industrial robots, there are numerous other conceivable applications; for example, extremely flat door or gate motion sensors that can be hidden behind wallpaper, or drilling machines switching off automatically once the desired drilling depth is reached.

The chip is based on the SiGe-BiCMOS technology that is suitable for the highest frequencies, and was developed by IHP Innovations for High Performance Microelectronics. The chip design was provided by IHP and Silicon Radar GmbH. KIT was in charge of the design of the transmitting and receiving antennae, and their integration into the small package. The thin and flexible organic carrier material of the antenna was developed by Hightec MC AG, Lenzburg, Switzerland. The Finnish company SELMIC manufactured the ceramic housing and assembled the prototype. Based on studies and analyses of various possible applications, Robert Bosch GmbH developed the system design of the sensor, integrated the control electronics, and carried out the performance tests.


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