A CMOS z-axis capacitive accelerometer with comb-finger sensing

This paper reports the first design and experimental results of a z-axis accelerometer that utilizes the sidewall capacitance change of multi-conductor comb fingers. The accelerometer has a fully differential capacitive bridge interface and its fabrication is compatible with standard CMOS processes. The frequency response of the accelerometer is characterized both electrically and optically and about 9.3 kHz resonant frequency is measured, which matches MEMCAD simulation within 15%. Measured sensitivity is 0.5 mV/g with less than -40 dB cross-axis sensitivity, noise floor 6 mg/rtHz, and linear range from -27 g to 27 g.