A High-Temperature, Low-Noise Readout ASIC for MEMS-Based Accelerometers

This paper presents the development and measurement results of a complementary metal oxide semiconductor (CMOS) readout application-specific integrated circuit (ASIC) for bulk-silicon microelectromechanical system (MEMS) accelerometers. The proposed ASIC converts the capacitance difference of the MEMS sensor into an analog voltage signal and outputs the analog signal with a buffer. The ASIC includes a switched-capacitor analog front-end (AFE) circuit, a low-noise voltage reference generator, and a multi-phase clock generator. The correlated double sampling technique was used in the AFE circuits to minimize the low-frequency noise of the ASIC. A programmable capacitor array was implemented to compensate for the capacitance offset of the MEMS sensor. The ASIC was developed with a 0.18 mu m CMOS process. The test results show that the output noise floor of the low-noise amplifier was -150 dBV/root Hz at 100 Hz and 175 degrees C, and the sensitivity of the AFE was 750 mV/pF at 175 degrees C. The output noise floor of the voltage reference at 175 degrees C was -133 dBV/root Hz at 10 Hz and -152 dBV/root Hz at 100 Hz.