A 63 μg/√Hz Noise Floor and 14 pJ Power Efficiency Open-Loop MEMS Capacitive Accelerometer Using Closed-Loop Hybrid Dynamic Amplifier

MEMS capacitive accelerometer for the Internet of Things (IoT) applications is designed with open-loop structure rather than close-loop structure to achieve low power consumption. In the open-loop structure, voltage control readout technique is preferred for low cost. However, voltage control readout technique suffers from poor noise performance and low power efficiency (in terms of FoM) . In this paper, the weak feedback oversampling successive approximation readout circuit which merges the closed-loop hybrid dynamic amplifier with noise reduction technique is proposed to achieve low noise floor, high power efficiency and high accuracy. The proposed WFB-OSA based readout circuit is fabricated in a commercial 0.18 μ m 1.8V CMOS process. The measurement result shows that the circuit has achieved a noise floor of 63μg/√Hz and an FoM of 14pJ .