MEMS陀螺驱动数字闭环ASIC设计

Design of Drive Digital Closed-Loop ASIC for MEMS Gyroscope

针对MEMS陀螺,基于四阶机电结合ΣΔ调制器技术设计了一款驱动数字闭环电路。其中电容/电压转换电路（C/V转换电路）采用了开关电容电路。为了降低C/V转换电路的噪声,采用了相关双采样（CDS）技术和斩波开关技术。仿真结果表明,采用这两项技术后,C/V转换电路的噪声在1~10kHz附近达到了约20zF/Hz。数字信号处理部分的时钟由锁相环路（PLL）提供,并且片上PLL对陀螺驱动模态谐振频率进行了倍频。采用0.18μmCMOS工艺制作设计的专用集成电路（ASIC）。实验结果表明,驱动闭环电路能够成功起振,电路输出信号的信噪比达到112dB,1h的稳定性达到2.08×10-4。

A digital drive closed-loop for MEMS gyroscope was designed based on fourth-order elec- tro-mechanic ZA modulator technology. The switched capacitor circuit was used in the capacitance/voltage converter （C/V converter）. In order to reduce the noise of the C/V converter, both correlated double sampling （CDS） technology and chopper switch （CS） technology were used. The simulation results indi- cate that the noise of the C/V converter was reduced to 20 zF/√Hz at 1- 10 kHz. The clock for the digital signal processing was provided by phase locked loop （PLL）, and PLL on chip was utilized to multiply the natural frequency of gyroscope drive-mode. The designed ASIC was fabricated with 0. 18μm CMOS tech- nology. The test results show that the drive closed-loop can work successfully and the signal to noise ratio （SNR） of the output signal can reach to 112 dB, and the stability in 1 h can reach to 2. 08×10^-4.