Magnetic flux modulation with a piezoelectric silicon bridge for 1/f noise reduction in magnetoresistive sensors

Magnetoresistive sensors have plenty of applications in magnetic sensing areas, but magnetic and nonmagnetic 1/f noise severely degrades their low-frequency performances, especially detection sensitivity with hundreds of loss. In this paper, vertical motion flux modulation scheme with a piezoelectric silicon bridge is recommended for 1/f noise reduction, due to its effectiveness, simplicity and stability as well as moderate modulation efficiency. In our prototype sensor, the detection sensitivity was greatly improved to ~80 pT /√Hz at 1 Hz, which was near 300 times upgraded, when the detected magnetic field was transferred up to the resonance frequency of the piezoelectric silicon bridge.