Low-Noise Drive of a Micromachined Resonant Accelerometer with Separated Sensing and Actuation

Micromachined resonant accelerometer (MRA) is typically operated at its optimal drive amplitude to minimize nonlinear vibration noise. However, the drive voltage amplitude is set usually as low as 10 mV, which consequently results in low drive voltage signal to noise ratio (SNR). To increase the amplitude of the drive signal and thus improve its SNR, this paper proposes a resonator structure with separated drive and sensing electrodes and high ratio of sensing and drive comb teeth in two dual-ended tuning fork resonator. Experiments on MRA prototypes with separated drive and sensing scheme were conducted and compared with the usual multiplexed electrode scheme. The experimental results show that a reduction of 30% in the measured frequency noise and a bias instability of 1.05 μg have been reached by the proposed low-noise drive design.