Thermal Accelerometer Performance Enhancements through AC Biasing Schemes

MEMS Thermal accelerometers are typically driven and sensed entirely at DC, an approach that contributes to their relatively high drift and noise. This work presents several novel operation modes based on independent modulation of the heater and the detectors: DC heating and AC sensing, AC heating and DC sensing, and full AC. The improvement in noise density offered by modulating the detectors is measured, showing a 23% reduction as compared to pure DC operation. Both AC heating modes exhibited an order of magnitude less drift at 100 seconds than DC heating. These results demonstrate the substantial improvements modulated operating schemes can offer for both noise and ultra-low frequency stability in thermal accelerometers.