Low power 3-axis Lorentz force navigation magnetometer

Demonstrated here is a MEMS magnetometer fabricated with the ST Microelectronics THELMA process that uses a single MEMS structure to detect magnetic flux in two axes. The device is comprised of a single Lorentz force actuator where the resulting shuttle motion is detected in two axes using differential in-plane capacitive sensing electrodes and a single-ended out-of-plane electrode. Three axis magnetic flux sensing is achieved using two perpendicular structures on the same die. The device is intended for electronic compass navigation applications and using a total of 300 µW of drive power has a 3-axis angular resolution of 0.8 degrees/rt-Hz in California, USA.