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Magnetic sensor works despite interference
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09/06/2008
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A 3-D magnetic field sensor has been developed by the Fraunhofer Institute for Integrated Circuits IIS in Erlangen that can work without screening.
Several sensors are arranged in a cell in such a way that they can measure all three components of a magnetic field in one place. If two such cells are placed on a chip, the sensor measures not only the magnetic field, but how it changes with position. According to IIS team leader, Dr Han-Peter Hohe, “This sensor enables us for the first time to identify magnetic interference fields as such and to separate them from the useful field. The sensor works perfectly even when the interference field is considerably larger than the useful field, there is therefore no need for shielding.”
Applications are seen in car mirrors and seats, in order to be able to move them to pre-set conditions chosen by individual drivers. The sensors detect where a magnet is in the mirror or seat in order that a motor can move it to the desired position.
The sensors are made using standard CMOS techniques and can be used at up to 150 deg C.
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Author
Tom Shelley
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