Hybrid silicon microaccelerometer system with CMOS interface circuit

Abstract

This paper presents a hybrid microaccelerometer subsystem consisting of an all-silicon /spl mu/g capacitive microaccelerometer and a low noise CMOS capacitive interface circuit. This accelerometer has a measured sensitivity of 1.4pF/g for a device with 2mm /spl times/ 1mm proof mass and 1.4/spl mu/m air gap. The calculated mechanical noise floor for the device is 0.39/spl mu/g/vHz in atmosphere. The circuit has a 95dB dynamic range; a low offset of 370/spl mu/V and can resolve better than 75aF. The overall sensitivity of the complete module is measured as 160mV/g with a noise floor of 3.6/spl mu/V/vHz (-110dBV/vHz), indicating that the current system is capable of resolving about 20/spl mu/g/vHz.