Improved Magnetic Frequency Conversion Approach for Magnetoelectric Sensors

Thin-film magnetoelectric sensors reach a sensitivity in the picotesla range around the resonance frequency of the mechanical structure. Using magnetic frequency conversion, a magnetic low-frequency signal can be transferred to the sensor's resonance frequency. However, the required additional large carrier signal leaks to the sensor's output with a large amplitude, requiring a wide dynamic range of the sensor electronics. In this paper, it is shown that the unbalance of the magnetostriction curve is responsible for this leakage and that a suppression approach is devised. After theoretical analysis of the nonlinear magnetostriction characteristic, a carrier suppression is achieved through balancing by an altered signal excitation. A suppression of the carrier signal of about three orders of magnitude is measured. Thus, the requirements regarding analog-to-digital conversion can be reduced.