Angular magnetic field sensor for automotive applications based on magnetic tunnel junctions using a current loop layout configuration

An angular magnetic field sensor for automotive applications based on magnetic tunnel junctions has been designed. Using magnetic tunnel junctions, the power consumption has been reduced by a factor of 1000 with respect to the one based on Hall sensors and the working distance has been increased. The standard Wheatstone bridge configuration is replaced by an electrical circuit based on a current loop layout. Using this configuration, the balancing of resistance is not necessary as for a Wheatstone bridge that can be a bottleneck when using magnetic tunnel junctions. The field to be measured is produced by a multipolar magnetic seal integrated in a wheel bearing. To obtain an angular sensor, four blocks of tunnel junctions in series have been used and with an appropriate sensor design, the two signals with a 90° phase shift required for an high accuracy angular measurement have been obtained.