A Technique to Enhance the Frequency Bandwidth of Contactless Magnetoresistive Current Sensors

Isolated wideband current measurement is required in many power electronic converters when the switching frequency is above 1 MHz. Typically current passing through a printed circuit board trace induces a highly nonuniform magnetic field which varies as a function of frequency and position relative to the trace. This paper proposes a technique to increase the frequency bandwidth of anisotropic magnetoresistive (AMR) current sensors and simultaneously to intensify and normalize the field detected by the sensor in the frequency range of interest, i.e., DC-5 MHz. We demonstrate experimentally that the proposed technique yields significant enhancement in detection bandwidth of AMR current sensors.