A low-power low-noise dual-chopper amplifier for capacitive CMOS-MEMS accelerometers

This paper reports a novel dual-chopper amplifier (DCA) and its application to monolithic complementary metaloxide semiconductor-microelectromechanical systems accelerometers. The DCA design minimizes the power consumption and noise by chopping the sensing signals at two clocks. The first clock is a high frequency for removing the flicker noise while the second clock is a significantly lower frequency to keep the unit gain bandwidth low. A monolithic three-axis accelerometer integrated with the DCA on the same chip has been successfully fabricated using a post-CMOS micromachining process. The measured noise floors are 40 μg/√Hz in the x- and y-axis and 130 μg/√Hz in the z-axis, and the power consumption is about 1 mW per axis.