Theoretical Model and Experiments of Resonance Frequency Shift by LC Tuning in Magnetoelectric Sensor

In this work, the authors present the resonance frequency shift of the magnetic sensor with Terfenol-D/PMN-PT heterostructure by LC tuning. A custom-built low noise voltage pre-amplifier is used to convert the weak signal induced by magnetic field into an output voltage. A practical noise model is established to theoretically analyze the variation of noise level of LC tuning magnetoelectric (ME) sensor. Both the theoretical analysis and experimental results indicate that LC tuning is an effective way to adjust the resonance frequency and reduce the equivalent magnetic noise (EMN). The resonance frequency of the LC tuning ME sensor can be shifted from 54.8 kHz to 24.8 kHz, with the maximum responsivity being 131 V/Oe@24.8 kHz. Furthermore, the EMN is as low as 0.22 pT/Hz(1/2)@24.8 kHz, which indicates a significant reduction from 0.54 pT/Hz(1/2) at the same frequency without LC tuning.