硅微谐振式加速度计相位控制环路优化研究

硅微谐振式加速度计(MSRA)凭借其潜在的高精度特点成为微加速度传感器领域的重点研究方向之一.相位环路的控制精度直接决定了MSRA的测量精度.在对MSRA工作机理进行简要分析的基础上,着重研究了现实验室加速度计样机的相位控制环路,分析了其相位误差的来源,并在原有环路滤波器的基础上增加了一种带参考电压的PI校正控制环节.实验结果表明,增加PI校正环节后,组成的四阶二型锁相环路可以使差分频率输出与温度线性拟合的相关系数从0.96291提高至0.98863,在±20 g量程围内,非线性度从430 ppm降低至154 ppm,硅微谐振式加速度计的零偏稳定性在常温下达到8.64 μg.

Study on Optimization of Phase Control Loop for Micromachined Silicon Resonant Accelerometer

Micromachined silicon resonant accelerometer (MSRA) with its potential high accuracy has become one of the key research directions in the field of micro accelerometers.The control precision of the phase loop directly determines the measurement accuracy of MSRA.Based on the brief analysis of the working mechanism of MSRA,the phase control loop of the accelerometer in the laboratory was studied emphatically,and the source of the phase error was analyzed,and on the basis of the original loop filter,a PI correction control loop with reference voltage was added.The experimental results show that after adding the PI correction,the fourth order and second type phase locked loop can make the correlation coefficients between differential frequency output and temperature linear fitting increase from 0.96291 to 0.98863,the nonlinearity reduces from 400 ppm to 154 ppm with the range of ± 20 g,the zero bias stability of silicon micro resonant accelerometer is 8.64 μg at room temperature.