04 novembre 2012
AN INTEGRATED 3D COMPASS
Contact : Gilles Gaudin

The 3 local magnetic field components Bx, By, and Bz are derived from the voltages measured across the 4 sensors (white rectangles representing a magneto-resistive stack) placed on the 4 sides of the pyramidal substrate.

We developed at the PTA a new 3D magnetometer concept, fully integrated, more compact, more accurate and more efficient than current solutions. We fabricated a first generation prototype. This magnetometer is perfectly suitable for mobile applications of spatial localization requiring a large autonomy.

 

More and more portable consumer devices such as watches, mobile phones, GPS, … use an electronic compass to position the device in space. These compasses measure the amplitude and the direction of the magnetic field. They use 3 axis magnetometers, so called 3D, whose market is growing fast. Current technologies are based on magneto-resistive sensors. They individually have a large sensitivity but manufacturing 3D magnetometer requires assembling at least two non-coplanar sensors. This leads to a hybrid device, expensive to produce, bulky and delicate, and, more importantly, presenting a limited resolution due to systematic errors in the assemblage.

 

We recently filed a patent application for an integrated 3D magnetometer providing an innovative solution to these problems. In this magnetometer, the three components of the magnetic field are derived simultaneously by several magneto-resistive sensors integrated on the same substrate (Fig.), and having same intrinsic sensitivity, resolution and thermal drift. It allows to significantly simplify the compensation of these drifts. Beside a much simpler and less expensive manufacturing process, this type of magnetometer offers greater compactness, greater sensitivity and a reduced consumption. The second generation is currently being fabricated in the PTA. It benefits from optimized magnetic stacks that should place it at the sensitivity state of the art. This magnetometer will be easily implemented into a mobile system to be used as a low power consumption integrated micro-compass.

 

Maj : 29/04/2014 (1010)

 

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