Accurate Data Acquisition Circuit for MEMS Accelerometer

Microsensor systems that can monitor diverse physical variables, such as location, accelerometer, angular velocity, and fluid properties to determine the external environment, have evolved significantly over the recent decade. The prevalence of advanced electronic integrating MEMS components has increased in consumer electronics. Due to their exceptional attributes concerning size, precision, power efficiency, and durability, MEMS sensors are used in a broad range of applications, including computing, mobile devices, tablet devices, as well as in airplanes and missiles etc. They are also utilized for medical applications, such as fall detection sensors to monitor elderly patients and car airbag activation. Owing to its advantages, it demands a highly effective and efficient MEMS accelerometer that can sense even the minute changes (capacitance) in the system and transform those changes to the appropriate voltage for subsequent signal processing. Low noise interface circuits are presented that can detect changes in capacitance ranging from 1p to 16pF and have a minimum resolution of 0.55fF. A detailed characterization of the capacitance to voltage converter (CVC) is described. As the bandwidth of the accelerometers is low, it is necessary to reduce the low-frequency noise of the front-end system. The major objective is to design and implement a read-out circuit that will enable the accelerometer sensors to have excellent dynamic range and resolution. The front-end of the read-out circuit is a low-noise, high-performance Charge-sensitive pre-amplifier. The high-resolution oversampling ADC with active integrators and dynamic comparators makes up the read-out circuit's back end. The proposed system demonstrates the front end and back-end implementation of the read-out circuit for a capacitive MEMS accelerometer at the circuit level. The implementation of the read-out circuit is done using the Cadence Schematic design tool Virtuoso, and simulations are done using Spectre Simulator.