一种集成SAR-ADC的电容式MEMS陀螺仪高精度模拟接口电路

提出一种为MEMS振动陀螺仪设计的驱动和检测接口电路。 第一步采用通用级和TIA得到低噪声C/V转换, 同时集成采样率1.25 MS/s的14位SAR-ADCs, 将驱动和感应模式的信号转换到数字域。采用这种策略, 模拟电路的复杂性被降低, 数字域的信号可以更精确操作。此接口适用于共振频率为3~15 kHz的MEMS 陀螺仪。此电路在0.18μm CMOS工艺流片。实验结果显示, 在3.5 kHz频率下, 输出电容的噪声密度为0.03 aF/√Hz。

A High-Resolution Analog Interface for Capacitive MEMS Gyroscope with Integrated SAR-ADC

The authors present a drive and sense interface for MEMS vibratory gyroscopes. A gm-stage and a TIA are employed as the first stage to achieve low-noise C/V conversion. The signals of both drive mode and sense mode are converted to digital domain by integrated 1.25 MS/s 14-bit SAR-ADCs. With this strategy, the complexity of the analog circuit is reduced, and the signal in digital domain can be manipulated more accurately. The interface is applicable for the MEMS gyroscopes whose resonant frequency is from 3 kHz to 15 kHz. The circuit is designed in a 0.18μm CMOS process. Experimental results show that the capacitive noise density of the output is achieved to 0.03 aF/√Hz at 3.5 kHz.