110-g, 7-μg/√Hz, Closed-Loop MEMS Accelerometer With Up To 5-kHz Bandwidth Through State-Space Control

The research introduces a novel micro-electro-mechanical system (MEMS) force-feedback accelerometer with board-level electronics and digital output for wide dynamic range and wide bandwidth applications. The sensor has a die area of 4 × 3 mm2 and is fabricated in a conventional 30-µm-thick capacitive epitaxial process from STMicroelectronics. In order to match the simultaneous targets of 100-g full-scale range, sub-10-µg/√Hz noise density and over-5-kHz bandwidth, the used approach is based on 1)the use of a digital regulator, 2)a regulator sized through the state-spacevariables, and 3)a tuning to near-zero electrostatic stiffness. Experimental results match the three targets above, with a programmable -3dB bandwidth up to 5kHz. Additional parameters are demonstrated, such as 0.1% linearity error up to about 110g and 6 µg stability up to 2000s observation intervals. After calibration across the 10°C to 85°C temperature range, the scale factor is stable within 240ppm and the offset drift residuals are within 530 µgrms.