A low noise capacitive MEMS accelerometer with anti-spring structure

• Published in: Sensors and actuators. A. Physical. Vol. 296; pp. 79 - 86
• Main Authors: Zhang, Hongcai, Wei, Xueyong, Ding, Yanyu, Jiang, Zhuangde, Ren, Juan
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01.09.2019; Elsevier BV
• Subjects: Accelerometers; Allan deviation; Anti-spring design; Background noise; Capacitive accelerometer; Converters; Frequency drift; Linearity; Low noise; Microelectromechanical systems; Noise sensitivity; Nonlinearity; Parameter estimation; Seismic application; Seismic design; Sensitivity analysis; Sensors; Thermal effect; Allan deviation; Thermal effect; Frequency drift; Low noise; Seismic application; Anti-spring design; Capacitive accelerometer
• ISSN: 0924-4247; 1873-3069
• DOI: 10.1016/j.sna.2019.06.051

[Display omitted] •A low noise capacitive MEMS accelerometer is designed and characterized.•The sensitivity and non-linearity of fabricated MEMS accelerometer are respectively 53 fF/g, 0.03% by the sigma-delta modulator, while the CVC method is 3.78 mV/g with the non-linearity 0.04%.•The frequency dynamic range is 0–158 Hz with a sensitivity non-distortion of ±0.1 dB. This work reports a capacitive MEMS accelerometer designed for seismic applications. The asymmetrical anti-spring structure is used and the device is microfabricated using SOI technology. Two capacitive readout methods, namely, capacitance-to-voltage-converter (CVC) and a commercial sigma-delta modulator, are introduced for comparison in the device characterization. For both methods, the accelerometer has a frequency dynamic range of 0-158 Hz. The sensitivity and non-linearity of the sensor is 53 fF/g (21.3 mV/g), 0.03% by the sigma-delta modulator, while the CVC method is 3.78 mV/g with the non-linearity 0.04%. As for the resolution, both methods have detected the lab's background noise of 11.5 μg/Hz at 0.03 Hz and have exhibited the resolution of the sensor is better than 10 μg/Hz. Regardless of the difference in parameter selection for the circuits, the CVC method has a much lower noise floor (51.8 ng/Hz at 1 Hz) than sigma-delta readout configuration (10 μg/Hz at 1 Hz). The proposed MEMS accelerometer based on anti-spring structures shows its high sensitivity and low noise performance, demonstrating its potential in seismic applications.