Low frequency excess noise source investigation of off-diagonal GMI-based magnetometers
Résumé
The impact of low frequency magnetization fluctuations on the equivalent magnetic
noise of GMI sensors has recently been investigated [1]. It appears that this noise source may
explain the low frequency excess noise exhibited by such sensors [2], in the 1/f regime. As a
consequence, we propose to extend the noise model of off-diagonal GMI-based
magnetometers presented in [2], to this regime. The model, based on classical GMI equations,
includes magnetization fluctuation noise sources. The equivalent magnetic noise level is then
computed from the sensitivity of each term of the sensing element impedance matrix to the
magnetization angle at the static working point (for both axial and circumferential static
magnetic field) and to conditioning circuitry. We have obtained new criteria for optimizing the
conditioning of the sensor signals. We highlight key parameters of the intrinsic properties of
the sensing element responsible for the ultimate equivalent magnetic noise performance.
Preliminary results lead to an expected equivalent magnetic noise (cf. figure 1), at 1 Hz, in the
range of 10 pT/√Hz, for physical GMI properties and conditioning parameters similar to
those employed in [2].
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References:
[1] C. Dolabdjian, B. Dufay, S. Saez, A. Yelon and D. Menard, Is low frequency excess noise
of GMI induced by magnetization fluctuations?, International Conference on Materials and
Applications for Sensors and Transducers, ICMAST, 2013.
[2] B. Dufay, S. Saez, C. Dolabdjian, A. Yelon and D. Menard, Characterization of an
optimized off-diagonal GMI-based magnetometer, IEEE Sensors Journal, vol. 13, no. 1
(2013), pp. 379—388.
Domaines
Electronique
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