Determination of the aging offset voltage of AMR sensors based on accelerated degradation test

Usually Anisotropic Magnetoresistance angle sensors are configured with two Wheatstone bridges, but an undesirable offset voltage included in the sensor output affects its accuracy. The total offset voltage combines a voltage due to resistance mismatches during manufacturing and a voltage from inequalities in the magnetic sensitivity. This paper focuses on identifying a consistent trend between the bridges´ offset voltages. Compared with previous studies that focus on lifetime tests using high temperatures, this research uses temperature cycling to study offset voltage and sensitivity variations due to aging effects. A consistent trend between the bridges´ offset voltages could not be found. The two offset components can add to or subtract from each other and their interaction can change over time due to variations in the sensor´s material properties. To achieve a precise angle measurement, the offset voltage must be compensated continuously over the entire sensor lifetime.