A Signal Conditioning ASIC with High Precision and Low Noise for MEMS Accelerometers

This paper proposes a high-precision signal conditioning Application-Specific Integrated Circuit (ASIC) for capacitive microelectromechanical systems (MEMS) accelerometer sensors. The capacitor-voltage(C-V) converter adopts a time-multiplexed method, thus indirectly realizing full-differential signal processing and suppressing the effects of common-mode signals and parasitic capacitance. An adjustable array of compensation capacitors is also incorporated in the C-V converter to effectively suppress the offset voltage and nonlinearity of the circuit with the correction of the sensing element. The main signal path of the system is based on a fully differential design, and to effectively suppress the offset voltage and low-frequency noise in the system, an auto-zeroing technique is used with correlated double sampling. The ASIC is fabricated in a 0.18 μm CMOS process. The results show that the overall acceleration system has a range of ±2g, a supply voltage of 3.3V, a total system power consumption of 4.95mW, a nonlinearity error of 0.075%, a noise floor of 0.76μg/√Hz, and a bandwidth of 10kHz. The application-specific integrated circuit for signal conditioning in this thesis realizes the performance of high precision, low offset, and low noise in an open-loop topology. It can be applied to many types of MEMS accelerometers.