GMR Revolution Sensors for Automobiles

In order to apply Giant Magneto-Resistive (GMR) elements to revolution sensors for automobiles, we studied an annealing effect upon GMR elements. After the GMR elements were annealed with the optimized condition, they showed sufficient temperature stability for automobile applications, as well as large MR ratio. The GMR elements were integrated with a sensing processing IC without any damage during the GMR wafer process. Sensitive sensor properties were obtained, especially the repeatability was three times better than that of a semiconductor Hall revolution sensor, which was due to that the integration of the GMR element with IC prevented noise and the signal output of the GMR element was one order higher than that of the semiconductor Hall revolution sensor.