A 5-V 555-μW 0.8-μm CMOS MEMS capacitive sensor interface using correlated level shifting

This paper describes a fully differential low-noise switched-capacitor (SC) readout circuit that is intended for MEMS capacitive inertial sensors. The circuit uses a variation of correlated level shifting (CLS) technique to reduce the opamp finite gain error as well as to minimize the effects of opamp offset and low-frequency noise. The readout circuit is designed and laid out in a 0.8 μm CMOS process. For the purpose of simulations, the MEMS capacitive sensor is emulated by a pair of differential variable capacitors in Verilog-A. Post-layout simulation results demonstrate that the circuit achieves a capacitance noise floor of ~0.25 aF/√Hz at 500 Hz with a sensitivity of 12.42 mV/fF. The circuit consumes 555 μW from a single 5 V supply.