A 0.18-µm CMOS time-domain capacitive-sensor interface for sub-1mG MEMS accelerometers

Abstract

A high-resolution capacitive-sensor interface for sub-1mG MEMS accelerometers is presented herein. A time-domain capacitive-sensor interface based on a relaxation oscillator with noise reduction is proposed to achieve a high resolution. A prototype interface is fabricated using a 0.18-µm CMOS process. The prototype is linked with a sub-1mG MEMS accelerometer, and its performance is investigated experimentally. The results confirm that the proposed interface is able to detect sub-1mG acceleration with a signal-to-noise ratio of 90.3 dB (an acceleration noise-floor of 9.0 µG/√Hz with a bandwidth of 12 Hz).