A new GMR sensor based on gradient magnetic field detection for DC and wide-band current measurement

The traditional isolating current detection method based on GMR can hardly meet the wide-band DC current detection requirements in harsh environment. This paper proposes a method using a GMR current sensor based on magnetic field gradient detection. The GMR sensor is mounted in a fine tuned condensed gradient field which is optimized by the finite element analysis. The noise due to the coupling between the amplifier circuits and the magnetic field are highlighted and analyzed by a six voltage source model. Problems on parasitic parameters are also addressed. Finally, a prototype with 1MHz sensing bandwidth is fabricated, and the experimental results fully validate the design method.