A low-power differential readout interface for capacitive accelerometer-based SHM applications

• Published in: Analog integrated circuits and signal processing Vol. 112; no. 1; pp. 161 - 174
• Main Authors: Shahbaz, Muhammad Aaquib, Khan, Fahd, Jawed, Syed Arsalan, Amin, Syed Usman, Jabbar, Muhammad Junaid, Iftikhar, Anas Bin, Bhatti, Muhammad, Aseeri, Mohammed A., Alghamdi, Majed S., Noor, Radwan M., Alalyani, Hamoud M., Obeid, Abdulfattah M.
• Format: Journal Article
• Language: English
• Published: New York Springer US 2022; Springer Nature B.V
• Subjects: Accelerometers; Circuits and Systems; CMOS; Electrical Engineering; Electrical measurement; Engineering; Leak detection; Microelectromechanical systems; Sensitivity; Sensors; Signal,Image and Speech Processing; Structural health monitoring; CMOS; Switch capacitor (SC); Accelerometer; SHM; MEMS; Readout interface (ROI); Monolithic
• ISSN: 0925-1030; 1573-1979
• DOI: 10.1007/s10470-022-02034-x

This work presents a power-efficient differential readout interface with digital output and negative force-feedback for capacitive MEMS accelerometers. The readout interface is designed for the monolithically integrated MEMS accelerometer embedded in the same CMOS die; however, it can also be used for external sensors for structural health monitoring applications. The readout interface is fabricated using a 0.18 µm CMOS 1P6M process with effective dimensions of 200 µm × 200 µm along with on-chip voltage/current biases and a digital controller. The electrical measurement results demonstrate a configurable readout sensitivity of 160 mV/g to 1.12 V/g with a noise floor of 100nV/√(Hz) equivalent to 350 µg/√(Hz). The measured dynamic range is 72 dB (1 mg to 4 g) and the peak SNDR of 66 dB is achieved for an input of 2 g. The readout interface has been tested and characterized with an external tri-axial accelerometer ADXL335 inside the lab using an electromagnetic vibrator and also in the field for pipeline leakage detection scenarios using the acceleration-gradient technique. The measured in-lab acceleration testing exhibits a 99% normalized matching with the electrical testing, establishing feasibility through extrapolation of the measurement results with an external sensor, of the readout interface for high-sensitivity on-chip and off-chip MEMS accelerometer sensors.