MAGNETOMETER WITH PULSE-EXCITED MINIATURE FLUXGATE SENSOR

Jan Kubík – Michal Janošek – Pavel Ripka

   Fluxgate sensors with racetrack cores manufactured with printed circuit board technology are described. Their properties as results of FEM modelling and experimental measurements with sine wave excitation current are given. An alternative signal extraction method using gated integrators is described for short current pulse excitation of these sensors, reducing noise over traditional 2nd harmonic detection. A feedback-operated magnetometer with pulse excited PCB sensor is described using this detection technique. 14 840 V/T and 1313 V/T sensitivity in closed-loop and open-loop respectively was achieved for sensor IIA (9.6 kHz, 300 mA pp 12.5 % duty cycle excitation current). The maximum linearity error has been measured as 80 ppm of full-scale range 100 μT. The stability of magnetometer offset was 8.3 nT in 2 hours. Noise measurement resulted in PSD of 96 pT/√Hz @ 1 Hz.

Keywords: fluxgate sensor, printed circuit board, pulse excitation, gated integrators, signal extraction, magnetometer

[full-paper]