摘要
为了改善微机电系统(MEMS)电容式加速度计的噪声特性,提出了一种基于开关电容的低噪声闭环接口电路。该电路采用电荷积分器作为前级预放大装置,对寄生电容不敏感,而且具有非常低的噪声。采用相关双采样(CDS)技术消除了1/f噪声和运算放大器失调电压的影响。同时,为了改善系统的动态响应特性,反馈部分采用积分电路,提高了系统阻尼比和响应速度。利用电荷泻放通道实现了自检测功能。采用0.5μm CMOS工艺完成了版图设计,仿真结果表明,系统灵敏度为0.115V/g,非线性度<0.12 %,可检测的最小加速度为20μg,自检测输出与自检测电压成正比。
A low noise closed-loop interface circuit based on a switched-capacitor is presented to improve the noise performance of a MEMS capacitive aeeelerometer. A charge integrator is adopted as pre-amplifier, which is insensitive to parasitic capacitance and has a very low noise level. The Correlated Double Sampling （CDS） technique is applied to eliminate the 1/f noise and the offset of an operational amplifier. Meanwhile, in order to improve dynamic response performance, an integration circuit is introduced to enhance the damping ratio of system and to increase the response speed. The self-test function is also realized by utilizing the same route with charge-discharging. Finally, an elaborate lay out design with 0.5μm CMOS process is completed. The post-simulation results indicate that the sen sitivity of the system is 0. 115 V/g, nonlinearity is less than 0. 12%,minimum acceleration detected can be up to 20μg and the self-test output is proportional to the self-test voltage.
出处
《光学精密工程》
EI
CAS
CSCD
北大核心
2009年第6期1379-1384,共6页
Optics and Precision Engineering
基金
Supported by the National Hi-Tech Research and Development Program of China (863 Program)(Grant No .2008AA042201)
关键词
加速度计
闭环控制
自检测
开关电容
接口电路
accelerometer
closed loop control
self-test
switched-capacitor
interface circuit
