Reduction of Noise in Fundamental Mode Orthogonal Fluxgates by Optimization of Excitation Current

Butta, Mattia; Sasada, I.

doi:10.1109/tmag.2011.2152379

Cited by 40 publications

(31 citation statements)

References 10 publications

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“…Despite agreement with experimental measurements in the white noise region, the previous model does not include the 1/f low frequency excess noise usually observed in measured spectra [4], [5], [6], [7]. Further improvement of GMI based magnetometers requires better understanding of the origins of this noise.…”

Section: Noise Model a White Noisementioning

confidence: 75%

“…Indeed, in order to minimize the magnitude of the excess noise at 1 Hz, it is necessary to obtain low values of the imaginary part of the complex magnetic susceptibility. This factor depends upon several working condition parameters such as the excitation frequency and the ratio between static and excitation current amplitude, and is the subject of current investigation [5], [4]. Thus, a more complete model, which should also include non-linear aspects of the GMI effect as presented in [23], would be of great interest.…”

Section: Discussionmentioning

confidence: 99%

“…However, cross-correlation measurements suggest that this low frequency excess noise is intrinsic to the sensing element and thus exhibits an intrinsic equivalent magnetic noise [14]. This conclusion is supported by research on the operating state of the sensing element presented in [5], [4], showing that the 1/f noise level depends strongly upon the parameters chosen for annealing of the magnetic wire and upon the DC bias current applied to the wire.…”

Section: Noise Model a White Noisementioning

confidence: 95%

“…In most cases, the output noise spectral density can usually be separated into a low frequency, excess, 1/f , noise, and a white noise floor [4], [5], [6], [7]. As highlighted in previous work [8], the white noise floor is mostly limited by the electronic conditioning noise level.…”

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confidence: 96%

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Low Frequency Excess Noise Source Investigation of Off-Diagonal GMI-Based Magnetometers

et al. 2017

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Abstract-The equivalent magnetic noise spectral densities of off-diagonal GMI based magnetometers exhibit significant low frequency excess noise, proportional to 1/f noise. As it represents a serious limitation to the ultimate sensing performances of high sensitivity magnetometers, possible sources of this 1/f noise are under investigation. Low frequency magnetization fluctuations have been proposed as the noise source in the case of classical GMI-based sensors. Here, we apply this model to off-diagonal GMI-based magnetometers. This requires the inclusion of magnetization fluctuation noise sources, in addition to white noise sources from electronic conditioning in the GMI effect equations. A pessimistic scenario is presented, predicting the upper limit of low frequency excess noise from material characteristics. 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. Based on this, it appears that magnetization fluctuations similarly affect all modes of operation of the two-port network sensing element, inducing identical impedance fluctuations. It also appears that this noise depends only upon the static equilibrium condition. This condition is governed by the effective anisotropy of the magnetic wire and by both axial and circumferential static components of the working point.

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Section: Noise Model a White Noisementioning

confidence: 75%

Section: Discussionmentioning

confidence: 99%

Section: Noise Model a White Noisementioning

confidence: 95%

mentioning

confidence: 96%

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Low Frequency Excess Noise Source Investigation of Off-Diagonal GMI-Based Magnetometers

et al. 2017

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“…the magnetic flux in the longitudinal direction is sensed by the pick-up coil). On the contrary, the sensitivity monotonically increases with the ac excitation current I ac (Butta et al, 2011) and therefore an increment of I ac can be useful to reduce the total noise even if a larger I ac could bring the core out of saturation.…”

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confidence: 99%

Orthogonal Fluxgates

Butta¹

2012

Magnetic Sensors - Principles and Applications

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Highly sensitive magnetometer based on the off‐diagonal GMI effect in Co‐rich glass‐coated microwire

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Usov

Nozdrin

et al. 2014

Physica Status Solidi (a)

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The design and performance of a magnetometer based on the off‐diagonal GMI effect in Co‐rich glass‐coated microwire are presented. The sensing element of the magnetometer is a 10‐mm long piece of Co–Fe–Ni–B–Si–Mo microwire with a small pick‐up coil of 85 turns wounded around the microwire. The electronics with a feedback circuit is used to register an electromotive force proportional to the external magnetic field applied along the wire axis. In the absence of the feedback current the magnetometer is capable of measuring a narrow range of magnetic fields, ±3.5 μT, in the frequency range of 0–1 kHz, the level of the equivalent magnetic noise being about 10 pT Hz−1/2 at a frequency of 300 Hz. The use of the feedback circuit increases the range of the measured magnetic fields up to ±250 μT. Photo of the giant magnetoimpedance magnetometer based on the off‐diagonal GMI effect in Co‐rich glass‐coated microwire.

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Reduction of Noise in Fundamental Mode Orthogonal Fluxgates by Optimization of Excitation Current

Cited by 40 publications

References 10 publications

Low Frequency Excess Noise Source Investigation of Off-Diagonal GMI-Based Magnetometers

Low Frequency Excess Noise Source Investigation of Off-Diagonal GMI-Based Magnetometers

Orthogonal Fluxgates

Highly sensitive magnetometer based on the off‐diagonal GMI effect in Co‐rich glass‐coated microwire

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