Compact MEMS magnetometers for inertial measurement units

This work discusses the performance, in particular in terms of minimum obtainable resolution, for Lorentz force based MEMS magnetometers, both accounting for technological constraints (minimum air gap, package pressure, standard industrial process, ...) and considering the final application in consumer electronics (bandwidth, noise, full scale range and linearity). Following an in-depth analysis of the operating principle, and carefully accounting for the damping behavior in the molecule-flow regime (typical for the used package), the expressions of the magnetometer sensitivity and intrinsic resolution (i.e. limited by thermo-mechanical noise) are derived. The predictions are compared to previous literature works and to recent experimental results obtained on a magnetometer designed and built using the ST Microelectronics ThELMA process. The given considerations are relevant for the co-design of a suitable low-power driving and readout electronics, an example of which is described in details.