Spring 2014 IAB & Research Review
March 5 - 6

Plenary 3:
Mo Li

Reducing the offset of Lorentz force magnetic sensors via current chopping

We present a method to reduce offset in micromachined Lorentz force magnetic sensors by chopping the Lorentz force bias current. By switching the polarity of this current, the sensitivity of the magnetic sensor alternates its sign whereas the offset remains the same. The proposed method significantly reduces the long-term drift of the magnetic sensor. A 9-hour measurement shows the maximum drift error is reduced from 600 μT to less than 1 μT, while Allan deviation measurements demonstrate that the long term drift is reduced by a factor of 120.