A Navigation-Grade MEMS Accelerometer based on a Versatile Front End

This paper presents a MEMS-based 5th-order Delta Sigma capacitive accelerometer. The Delta Sigma loop is implemented in mixed signal, the global 5th-order filter having a 2nd-order analog and a 3rd-order digital part. The system can be used with a wide range of sensors, because the mixed-signal front-end is programmable. The developed ASIC comprises a voltage-mode preamplifier, two parallel demodulators implementing CDS, and a 7-bit internally non-linear flash ADC. The latter drives a 3rd-order digital filter which can be configured for different sensor parameters in order to ensure overall loop stability and to optimize the noise performance. With a low-noise MEMS sensor, the system achieves a 19-bit DR and a 16-bit SNR, both over a 300-Hz bandwidth.