A Modulated Feedback Approach to Improve Closed Loop MEMS Accelerometer Bias Instability

Bias instability serves as one important performance specification for MEMS accelerometer. The bias instability is affected by 1/f noise. Conventional operation adopts the correlated double sampling (CDS) to reduce the 1/f noise, but is only feasible with switch capacitors. The paper proposes a novel and universal modulated feedback approach to improve the bias instability of closed loop MEMS capacitive accelerometer. The modulated feedback method is utilized to isolate the 1/f noise the electronic interface brings to the system. The comparison experiments are set up and the Allan Variance show significant improvement for the bias instability. We achieve the bias instability around 8μg after applying modulated feedback approach, making the closed loop MEMS accelerometer being able to enter high precision inertial sensor level.