A closed-loop switched-capacitor interface for high-quality microaccelerometer

This paper presents a closed-loop switched-capacitor interface for high-quality bulk micro-mechanical accelerometer. Analogue force feedback is realized to establish an electro mechanical closed-loop so as to improve the dynamic range. The feedback accuracy is guaranteed by applying bottom-plate sampling structure in the feedback controller. A proportional derivative controller is introduced to compensate the instability derived from the high-quality accelerometer, while offset cancellation structure is inserted to further improve the dynamic range. The chip measures 2.5 × 2.5mm² in Chartered 0.18μm CMOS process. Simulation results show that the whole accelerometer system offers ±1.3g input range with 0.25% non linearity from a single 6V supply, as well as a good degree of robustness.