A CMOS-MEMS gyroscope interface circuit design with high gain and low temperature dependence

This paper describes an interface circuit design for monolithic CMOS-MEMS gyroscopes, based on a novel differential difference amplifier (DDA) with high gain, low temperature and process dependence, low noise, and low power consumption. The DDA achieves a 4 fF equivalent transcapacitance with a 0.01%/° C temperature variation. The DDA-based interface circuit has been integrated with a z-axis gyroscope on a foundry CMOS chip. A 4.5 zF/ √Hz input-referred noise is achieved at 2 kHz, with a total power consumption of 4.25 mW. The gyroscope is fabricated with a post-CMOS bulk micromachining process and the device achieves a sensitivity of 1.2 mV/°/s and a noise floor 0.05°/s/ √Hz.