硅微谐振式压力传感器闭环频率跟踪电路

Closed Loop Frequency Tracking Circuit for Micro-resonant Pressure Sensor

为了精确、快速测量静电激励/压阻检测的硅微谐振式压力传感器在受到外界压力后频率的变化,设计了一种基于锁相环的闭环频率跟踪电路。通过对输入信号进行放大、滤波和移相以满足闭环自激振荡条件,然后利用锁相环电路进行信号的无相差频率跟踪,最后将锁相环输出信号转换为满足传感器激励要求的正弦信号。该电路具有良好的频率稳定(频率误差<1 Hz)和跟踪性能,实现了在18~30 kHz范围内频率无相差锁定。

In order to accurately and quickly measure the frequency of the silicon micro-resonant pressure sensor with electrostatic excitation/resistance detection after receiving external pressure,a closed-loop frequency tracking circuit based on phase-locked loop was designed.The input signal was amplified,filtered and phase-shifted to satisfy the closed-loop self-oscillation condition,and then the phase-locked loop circuit was used to track the phase-free frequency of the signal.Finally,the phase-locked loop output signal was converted into a sinusoidal signal that satisfies the sensor excitation requirement.The circuit has good frequency stability(frequency error<1 Hz)and tracking performance,and achieve frequency-free phase-locking in the range of 18~30 kHz.