Low-pressure small MEMS accelerometer using Sigma-Delta modulation

Encapsulation of MEMS accelerometers in vacuum is advantageous, since it allows integration with other sensors, leading to size and cost reduction. One technique to operate MEMS accelerometers in vacuum is the use of closed-loop Sigma-Delta modulation, which has many advantages. In this paper, the design of a vacuum encapsulated small size MEMS accelerometer (0.2 mm2) and the preliminary measured results are presented. Experimental devices were fabricated and operated in 2nd and 3rd order Sigma-Delta modulators, achieving a noise figure of 389 µg/√Hz for a bandwidth of 200 Hz and a measurement range of at least ±1 g.The first author is supported by FCT– Fundação para a Ciência e Tecnologia through the grant PDE/BDE/114563/2016. This work is supported by FCT with the reference project UID/EEA/04436/2013, COMPETE 2020 with the code POCI-01-0145-FEDER-006941.