A low noise CMOS charge sensitive preamplifier for MEMS capacitive accelerometer readout

This paper describes a low noise CMOS charge sensitive preamplifier for MEMS capacitive accelerometer readout circuit. This structure utilizes a feedback capacitance and switch´s technique to cancel the input parasitic capacitance and the offset voltage, and also uses an optimized noise input buffer stage to reduce low frequency noises, especially the flicker noise without increasing the complexity of the proposed circuit. The simulation result of the proposed circuit shows that an average noise reduction of 94% at low frequencies has been achieved compared with conventional folded cascode differential amplifier. The root mean square equivalent input noise is 4.0 nV/rtHz at 1 kHz.