An analog closed-loop SC accelerometer interface for a capacitive high-Q sensor element

This paper presents an accelerometer interface circuit using a vacuum packaged MEMS sensor element. In order to damp the sensor element, increase the linearity and improve the input range of the sensor, a closed-loop analog SC interface with a PD-controller is used. The theoretical input range of sensor is ±1.4 g while measured range of the sensor is from -0.7 g to +1.4 g. The interface achieves maximum non-linearity of 0.67% over temperature range of -40 to +85 °C. The sensor has bias stability of 11 μg and the noise density of 2 μg√Hz. The interface has been implemented in a 0.35 μm CMOS process with a total active area of 1.3 mm², and it consumes 2.4 mA from a 3.6 V supply.