MEMS Lorentz force magnetic sensor based on a balanced torsional resonator

We demonstrate an x-axis Lorentz force sensor (LFS) for electronic compass applications. The sensor is based on a 30 μm thick torsional resonator fabricated in a process similar to that used in commercial MEMS gyroscopes. The sensor achieved a resolution of 210 nT/√Hz with a DC supply voltage of 2 V and driving power consumption of 1 mW. Bias instability was measured as 60 nT using the minimum Allan deviation. This mechanically-balanced torsional resonator also confers the advantage of low acceleration sensitivity; the measured response to acceleration is below the sensor's noise level.