Double-Core GMI Current Sensor

A novel design of the giant magnetoimpedance contactless current sensor is presented. A double-core structure is used in order to improve the temperature stability. The temperature coefficient of sensitivity and offset drift are reduced to one-half compared to the single-core sensor. The linearity error decreases by a factor of three. Further utilization of an ac biasing (up to 200 Hz) of the double-core sensor suppresses the temperature offset drift by a factor of 30 (down to 0.6 mA/K) and increases the open-loop linearity to 0.5% for the 2-A range