Modeling of a Capacitive Σ-Δ MEMS Accelerometer System Including the Noise Components and Verification with Test Results

This paper presents a detailed SIMULINK model for a conventional capacitive Σ-Δ accelerometer system consisting of a MEMS accelerometer, closed-loop readout electronics, and signal processing units (e.g. decimation filters). By using this model, it is possible to estimate the performance of the full system, including the effect of individual noise components, operation range, scale factor, etc. The model has been verified through test results using a lateral accelerometer, full-custom designed 2
^nd
-order Σ-Δ readout electronics, and a signal processing unit implemented on PIC. The implemented system operates at 500 kHz sampling rate and has 0.53 V/g open-loop sensitivity, 58.7 μg/√Hz resolution, ±12g operation range, and 0.97e-6 g/(output units) scale factor, where these numbers are in close agreement with the estimated results.