A miniaturized magnetic-field sensor system consisting of a planar fluxgate sensor and a CMOS readout circuitry

We report on a miniaturized magnetic-field sensor system consisting of a fluxgate sensor fabricated in CMOS-compatible planar technology and a CMOS-ASIC for sensor supply, readout and signal processing using the second-harmonic principle with a feedback loop for zero-field operation. The system exhibits a sensitivity of 9.2 +/- 0.1 mV mu T-1 for a magnetic field range of +/- 90 mu T and a temperature range of 0 to 70 degrees C. The 3 dB bandwith is 300 Hz and a noise value of 30 nT Hz(-1/2) has been estimated. Using 5 V supply voltage, the power consumption of the system is measured to be 160 mW.