We report on a galvanic isolated current sensor that operates on the principle of the GMR-effect (giant magneto resistive effect). Due to an optimized combination of uniaxial and unidirectional magnetic anisotropy of the sense layer system the sensor response is temperature independent and linear at low currents. Higher currents are measured with a reduced sensitivity. By optimizing the sensor stack a good accuracy with an error less than 0.3 % is obtained in the industrial temperature range. The sensor system is capable of measuring DC, AC and pulse currents up to 20 MHz.