A closed-loop MEMS accelerometer with capacitive sensing interface ASIC

Abstract

A closed-loop MEMS accelerometer with capacitive sensing interface ASIC (application specific integrated circuit) is presented. The parasitic-insensitive switched-capacitor sample-charge architecture is used to implement the capacitive sensing, which is crucial to the case where sensor and interface ASIC are combined in a two-chip approach to implement the closed-loop MEMS accelerometer. Based on the 0.35 µm CMOS sensing interface ASIC, an accelerometer prototype has been implemented, in which force-rebalance with the lag-proportional–integral controller is applied to improve the system stability and frequency response performance, and the testing results indicate the sensitivity of the presented accelerometer is 650 mV/g, the full measurement range ±15 g, the non-linearity 0.098% and the noise floor 23.17 µg/rt-Hz.