An Ultra-Low Power CMOS Readout Circuit for a MEMS Resonant Accelerometer

This paper presents a modified pierce oscillator based ultra-low power CMOS readout circuit for a MEMS resonant accelerometer. Differential topology is adopted to make the readout circuit compatible with the MEMS sensing element and depress the common mode noise from amplitude control circuit and bias current source. A g
_m
regulated amplitude control strategy is proposed to avoid the MEMS resonator from strong nonlinear region without deteriorating its noise performance. Simulation results indicate the proposed readout circuit only consumes 1.8μW with a supply of 1.8V. Interfaced with a MEMS resonant accelerometer, it could realize a noise floor of 2μg/Hz
^1/2
but with 1000~10,000x lower power than published works.