硅微谐振压力传感器检测信号的幅值稳定性与频率跟踪性对其性能至关重要,但目前幅值控制与频率跟踪方法的非线性特征会造成谐振器振动频率的非线性变化,限制了传感器综合精度的进一步提升.为降低谐振器振动频率非线性变化的影响,基于自动增益控制(Automatic gain control,AGC)的线性化分析理论,建立高Q值硅微谐振压力传感器自动增益控制和相位补偿模型,分析AGC幅值控制和频率跟踪线性化的控制特性,以及相位补偿对闭环控制性能的影响.基于自动增益控制(AGC)的自激驱动被证实可使谐振器稳定工作于谐振频率,且保持幅值稳定,通过Simulink/PSpice建模仿真,验证非线性系统线性化分析的准确性.同时基于自动增益控制与相位补偿模型设计与制作的硅谐振压力传感器控制电路,经测试可使整表频率稳定性优于±0.05 Hz@采样周期5 ms,综合精度优于±0.02％FS,实现自动增益控制在谐振压力传感器的工程化应用,解决了谐振器频率跟踪非线性引起的传感器性能下降问题,可广泛应用于高Q值谐振器闭环控制.
Study on Automatic Gain Control and Phase Compensation Control for MEMS Resonant Pressure Sensors
The amplitude stability and frequency tracking of the detection signal of the silicon micro resonant pressure sensor are very important to its performance,but the nonlinear characteristics of the current amplitude control and frequency tracking methods will cause nonlinear changes in the vibration frequency of the resonator,which limits comprehensive accuracy further improvement of the sensor.In order to reduce the influence of the nonlinear change of the resonator vibration frequency,based on the linearization analysis theory of automatic gain control(AGC),the AGC and phase compensation model is established for the high-Q silicon micro-resonant pressure sensor.With the model,the control characteristics of AGC amplitude control and frequency tracking linearization,and the effect of phase compensation on closed-loop control performance are analyzed.The self-excited drive based on AGC has been proved to make the resonator work stably at the resonant frequency and keep the amplitude stable.Simulink/PSpice simulation verifies the accuracy of the linearization analysis of the nonlinear system.Afterwards,a control circuit is designed and fabricated based on the AGC and phase compensation model for the silicon resonant pressure sensor,which can make the frequency stability of the whole meter better than±0.05 Hz@sampling period 5 ms,and the comprehensive accuracy is better than±0.02％.The engineering application of AGC in resonant pressure sensors solves the problem of sensor performance degradation caused by the nonlinear frequency tracking of resonators.The study in this work demonstrates AGC and phase compensation control can be widely used in closed-loop control of high-Q resonators.
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