Giant magnetoresistive sensors for rotational speed control and current monitoring applications

Giant magnetoresistance sensors for rotational speed control (0-3200 rpm, anti-blocking system) and for current monitoring (0-2000 A) were fabricated and tested. A bridge design is used, where the individual sensors are spin valves (sv) with dimensions 200×3 μm². The ABS sensor uses flux guides for two of the sv elements, and has the other two sv´s inactivated, leading to a square wave output response to a magnetized wheel with n N-S poles (±0.2 V, rise time <30 μs at 320 rpm). The analog current monitoring system consists of 4 unshielded sv elements where 2 are inactivated. The sensor was tested for high current monitoring (0-2000 A AC, 50 Hz). It shows less than ±1.5% linearity deviation in this current range and a resolution of 35 μV rms/A for a sense current of 14 mA