改进的电容式微加速度计中电路噪声模型

为了在加速度传感器设计中准确预测系统电路噪声,优化电路设计参数,建立了改进的电容式微加速度计中的电路噪声模型.详细分析了电荷积分器中的运算放大器噪声、开关热噪声、驱动信号参考电压、寄生电容电阻对系统噪声的影响,分析了相关双采样对热噪声和1/f噪声的影响,建立了微加速度计系统的输入参考噪声公式,所建立的电路噪声模型对各个电路噪声源进行综合考虑,没有忽略噪声源间的相互影响.仿真和测试结果表明:所建立的电路噪声模型能够准确的预测噪声水平,且开关热噪声在高精度微加速度计中严重影响着系统噪声水平.

An improved circuit noise model in a capacitive micromachined accelerometer

In order to predict noise performance of capacitive micromachined accelerometer, optimize parameters of circuits, animproved electronic noise model is established in this paper. The influences of operational amplifier noise in charge integrator, switch thermal noise, reference voltage noise, parasitic capacitance and dead resistance to the noise performance of system are analyzed. The effect of correlated double sampling (CDS) to thermal noise and 1/f noise is considered. An input reference noise model for micromachined accelerometer is established, in which interaction between noise sources is considered. Simulated and tested results indicate that the noise model can predict noise level exactly, and the switch thermal noise plays an important role in high accuracy accelerometers.