A CAPACITIVE INTERFACE CIRCUIT WITH CAPACITOR MISMATCH AUTO-COMPENSATION FOR MEMS GYROSCOPE

摘要

In this paper, a capacitive interface circuit with capacitor mismatch auto-compensation has been designed and implemented for MEMS gyroscope. An on-chip capacitor array controlled by an 8-bit SAR logic circuit is selected to be connected in parallel with the minor one of the two differential gyroscope capacitors, making the two capacitors equal. The compensation progress takes eight periods of the clock at power-on and then will be turned off automatically. The chip is fabricated in a 0.35 μm CMOS process. The test of the chip is performed with a vibratory gyroscope on the condition of a closed-loop control in the drive mode, and the measurement shows that the minimum capacitive compensation is 3.5 fF. Within -300°/s to 300°/s of rotation rate input range, the nonlinearity is less than 0.1%.