Single resonator, time-switched, low offset drift z-axis FM MEMS accelerometer

The work presents principle of operation, design and test of a novel z-axis MEMS accelerometer realized through a single resonator, in which the differential readout is achieved sampling the two resonant frequency values obtained alternatively biasing suitable tuning electrodes in subsequent time intervals. An electronic oscillator sustains the MEMS resonator, providing a low-phase-noise signal to a frequency counter. The accelerometer shows a sensitivity of 1.3Hz/g, with linearity error lower than 1% up to 15g and a consumer-grade resolution of 160μg /√Hz. The key-feature of the proposed inertial sensor is that the ZGO (zero-g offset) thermal drift can be conceptually nulled. Preliminary demonstrations report values lower than 100 μg / K without post-acquisition compensation.