Offset Reduction in GMI-Based Device by Using Double-Frequency Bias-Current Modulation

In this paper, we investigate the effect of temperature variations on the off-diagonal giant magneto-impedance (GMI) response. This paper is based on a theoretical model describing the GMI-based sensor response. The modeling has been extended to include the resistivity dependence versus the temperature. It allows to calculate both temperature sensitivity and intrinsic magnetic field sensitivity, whose ratio leads to the determination of the magnetic field offset drift versus the temperature. Thanks to an original conditioning circuitry based on a double ac current excitation instead of the classical one, we achieved an improvement of the long-term stability and minimized the sensor temperature dependence. Experimentally obtained results have been compared with the expected offset drift for the classical GMI, and with the expected fluctuation reduction while adopting this technique, showing a relatively good agreement with the proposed modeling.