A 10 mW, 0.4 mu g/root Hz, 700 Hz Sigma Delta High-Order Electromechanical Modulator for a High-Q Micromechanical Capacitive Accelerometer

作者：Xu Honglin; Wu Junjie; Zhang Hao; Liu Haitao; Deng Qing

来源：IEEE Sensors Journal, 2018, 18(3): 1187-1194.

DOI：10.1109/JSEN.2017.2780279

• Switched capacitor
• interface circuit
• capacitive accelerometer
• high-Q
• phase compensation

A switched-capacitor sigma-delta (Sigma Delta) CMOS interface circuit for the closed-loop operation of a micromechanical capacitive accelerometer is presented in this paper. A distributed-feedback and feedforward topology is proposed to combine with a high-Q sensor element to obtain a sub-mu g/root Hz noise floor. The loop stability is implemented by damping the high-Q sensor element in the operation of electrostatic feedback force and heavy phase compensation, which introduces an extra zero to compensate the loop. Besides, the low-frequency loop gain is controlled by off-chip adjusting of distributed-feedback factor to keep the balance between the loop stability and noise shaping ability. The interface circuit is designed and fabricated in a standard 0.5-mu m CMOS process. The chip consumes 10 mW from a single 5-V supply. The measurement results show that the noise level is lower than 400 ng/root Hz, and the average noise equivalent acceleration density is 200 ng/root Hz over a 700-Hz bandwidth. The input range of the accelerometer is +/- 0.7 g resulting in a dynamic range of 125 dB over 1-Hz bandwidth. The measured sensitivity of 2.5 V/g is shown with a dc nonlinearity of 0.17%, and the bias instability is 19 mu g.

• 出版日期2018-2-1