Development of characteristic test system for GMR sensor

In order to test the characteristics of giant magneto-resistance (GMR) sensor comprehensively and accurately, a test system based on 3D Helmholtz coil is designed. The coil can generate sine magnetic field in the range of −10mT to 10mT, 0Hz to 500Hz in three vertical dimensions. The static and low-frequency characteristics of a GMR sensor are tested and analyzed. The dynamic test results reveal that GMR sensor should be applied in unipolar magnetic in its linear range in which case maximal error is still as large as 20% mainly caused by hysteresis. In order to increase the accuracy furthermore in measuring dynamic instantaneous magnetic induction, appropriate hysteresis compensation methods should be analyzed and applied in further research.