A 22-ng/ \surd Hz 17-mW Capacitive MEMS Accelerometer With Electrically Separated Mass Structure and Digital Noise- Reduction Techniques

• Published in: IEEE journal of solid-state circuits 2020-09, Vol.55 (9), p.2539-2552
• Main Authors: Furubayashi, Yuki, Oshima, Takashi, Yamawaki, Taizo, Watanabe, Keiki, Mori, Keijiro, Mori, Naoki, Matsumoto, Akira, Kamada, Yudai, Isobe, Atsushi, Sekiguchi, Tomonori
• Format: Article
• Language: English
• Subjects: Accelerometer; Accelerometers; Capacitance; Capacitors; closed loop; Electrodes; Force; force rebalance; mechanical resonance; micro-electromechanical systems (MEMS); Micromechanical devices; noise reduction; quantization noise; Servosystems
• ISSN: 0018-9200; 1558-173X
• DOI: 10.1109/JSSC.2020.2991533

A fully integrated micro-electromechanical system (MEMS) accelerometer with extremely low noise level (22 ng/ \surd Hz) and sufficiently low power consumption (17 mW) for emerging applications (such as infrastructure monitoring and next-generation oil and gas exploration) was developed. By applying concurrent operations of detection and control (enabled by a unique MEMS element) and reducing servo-signal leakage and noise caused by an interaction of 1-bit quantization and asymmetric mass deformation in the digital domain, a ninefold-lower noise level is achieved in comparison with state-of-the-art low-noise low-power MEMS accelerometers. The MEMS element was fabricated on 6-in Si/SOI/Si bonding wafers, while the detection and driver integrated circuits were fabricated as interface circuits with the standard 0.13- \mu \text{m} complementary metal-oxide-semiconductor (CMOS) process and the high-voltage 0.35- \mu \text{m} CMOS process, respectively. The power consumption of the developed MEMS accelerometer is 17 mW from 1.4-, 1.8-, and 12-V supplies, and it has an input range of ±0.55 g and bandwidth of 400 Hz.