Integrated Gigant Magnetic Resistance based Angle Sensor

An integrated GMR (giant-magnetic-resistance) sensor is presented for 360deg angular measurements of rotating magnetic fields in automotive applications. The spin-valve GMR-layers are directly applied to a standard semiconductor 0.22 mum CMOS process by vertical integration of the sensor-bridges atop of active circuitry. The entire integrated angle-sensor comprises 2 orthogonal magnetized GMR-bridges for sine and cosine signal measurements, and the subsequent signal conditioning circuitry. The entire angular sensor is designed to work in harsh automotive environment in a temperature range of -40degC to 150degC. The strength for best precision covers a wide range from 20 to 50 mT. The resulting angular information itself can be obtained by SPI-readout and calculating the arc-trigonometric function of the bridge signals with a resolution of >13 bit in an auxiliary microcontroller. After individual calibration to compensate for production spread an accuracy of typical 0.5deg is achieved.