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

Abstract

This paper reports an improved low-power low-noise dual-chopper amplifier (DCA) for capacitive CMOS-MEMS accelerometers. The new DCA employs an on-chip band-gap voltage reference to reduce the number of bonding pads and the complexity of the external circuits. The temperature drifting of the first-stage gain is reduced by using PMOS instead of NMOS as an active load. A prototype DCA with a three-axis accelerometer has been fabricated using the TSMC 0.35 mum technology. The number of required bonding pads is reduced from 21 to 14, and the temperature sensitivity is reduced from 1.2 times 10 ^-3 /degC to 5.4 times 10 ^-4 degC.