A 32.5μg/√Hz, 0.64mm 2 /Axis MEMS Accelerometer Using High-Voltage Pulse Excitation and Active Noise Cancelation Readout Technique

For wearable applications, the small size low noise MEMS accelerometer with high efficiency is required. However, the sensitivity of the MEMS sensor reduces with the sensor size scaling down, leading to deterioration of the circuit noise. To meet this challenge, the interface circuit with high-voltage pulse excitation (HVPE) and active noise cancelation readout technique is proposed. The HVPE reduces the circuit noise and the wire resistance noise significantly without introducing additional electrostatic force to the sensor. The drift and mismatch problems of the HVPE are addressed by three specific correction circuits. The power efficiency of the system is optimized by the capacitance-to-voltage converter with active noise cancellation and pulse current supply. The propose HVPE technique is demonstrated in an interface IC fabricated by $0.18\mu $ m BCD process and tested with a small size MEMS accelerometer (0.64mm²/axis). The measurement result shows that this IC has achieved a noise floor of $32.5\mu $ g/ $\surd $ Hz with 2kHz bandwidth and $80\mu $ W power consumption.