A capacitive MEMS accelerometer readout with concurrent detection and feedback using discrete components

This paper presents an analog readout method for capacitive MEMS accelerometers in which the feedback actuation and capacitive detection are achieved simultaneously on the same electrode set. The presented circuit operates in closed-loop for improved linearity, and it is constructed in a hybrid platform package in which off-the-shelf discrete components are used together with the silicon-on-glass micro-accelerometer. The system is developed as a practical solution to reduce the complexity of the readout circuit and the accelerometer without degrading the overall system performance. Experimental results demonstrate 17.5 micro-g per square-root hertz velocity random walk, and 28 micro-g bias instability. Considering the estimated full scale range of 20 g, the dynamic range of the sensor is calculated to be close to 124 dB.