Title: The Noise Measurement for Characterization of the Filter Order for Single-Axis Capacitive Microaccelerometer with Sigma-Delta Modulation

Date Published: 7-2-2024

Authors: C.Romero, R. Neyra

Keywords: Noise Measurement, Single Axis Capacitive Micro accelerometer, Sigma-Delta Modulation, Filter order

Abstract: This paper investigates the application of sigma-delta modulation (SDM) to reduce noise in single-axis capacitive micro accelerometers. SDM achieves this by oversampling the sensor output signal and employing a high-pass noise shaping filter. This process modulates the noise power spectrum, shifting the dominant noise components to higher frequencies where they can be effectively suppressed by the filter. Consequently, the signal-to-noise ratio (SNR) at the desired bandwidth is significantly improved, resulting in a higher-resolution output signal with a lower noise floor. The paper first analyzes the various noise sources inherent to single-axis capacitive micro accelerometers. It then explores how SDM can be leveraged to specifically target and mitigate these noise contributions. Furthermore, the paper proposes methodologies for determining the optimal filter order within the SDM architecture to achieve the desired trade-off between noise reduction and circuit complexity. Finally, the paper presents experimental results that validate the effectiveness of SDM in reducing noise in these accelerometers. The results quantify the improvement in SNR achieved by SDM, demonstrating its significant impact on the noise performance. This enhanced performance broadens the applicability of single-axis capacitive micro accelerometers to a wider range of applications with stricter noise sensitivity requirements.