Modeling and Simulation of High Performance Sixth Order Sigma-Delta MEMS Accelerometer

Abstract

MEMS fabrication process is an inherently rugged technology and has great potential to bring forth novel solutions on the harsh environment and critical applications. This paper reports on a very high performance closed-loop MEMS accelerometer targeted at inertial navigation applications. Motivation of this paper is to develop a high resolution inertial grade closed loop Accelerometer using the MEMS sensor fabricated at LEOS. The MEMS sensor with comb type structure has a sensitivity of 6 pF / g. This paper reports on the design and detailed simulation of signal conditioning circuit for MEMS accelerometer using a 6th order Sigma-Delta IC ADS-1278 provided by Texas Instruments. The functionality and the performance of the system were studied by P-Spice simulation. Signal-to-noise ratio (SNR) of 97.8dB and effective number of bits (ENOB) of 16 bits over a measurement range of +/-1g was estimated with an over sampling ratio (OSR) of 128.