Cross-Field Effect in a Triaxial AMR Magnetometer With Vector and Individual Compensation of a Measured Magnetic Field

Abstract

Magnetic field sensors based on anisotropic magnetoresistance (AMR) are widely used in many scientific and industrial applications. The AMR sensor sensitivity is superior to Hall probes and size and power consumption is superior to fluxgates. However, the noise properties and the temperature stability of AMR sensors are typically worse than for fluxgates. These properties define the typical applications—less precise vectorial or gradient measurements of the magnetic field within less than ±1 mT range. AMR sensors are typically calibrated for sensitivity, offset, and orthogonality errors. However, there is another important source of error—sensitivity to the magnetic field applied in the perpendicular direction to the measurement axis. This so-called cross-field error is inherent to AMR sensors and can influence the measurements significantly. Flipping (set/reset pulses) and closed-loop operation of the sensor can reduce the cross-field error. In this paper, we present a novel approach using full vectorial compensation of the measured magnetic field resulting in a complete elimination of the cross-field effect. The vectorial compensation provided superior results over alternative approaches that were also evaluated.