微悬臂谐振传感器闭环接口和嵌入式频率电路

设计了谐振式微悬臂梁传感器闭环接口和嵌入式频率读出电路。首先,谐振式微悬臂梁传感器和接口电路组成闭环自激振荡系统。为了提高该闭环系统的频率稳定性和频率跟踪性能,引入具有无相差频率跟踪的锁相环电路,并设计放大移相电路以满足闭环自激振荡条件。该闭环系统的频率稳定性可达±0.1Hz,并且能够实时跟踪悬臂梁谐振频率的变化。此外,单独设计了嵌入式的频率读出电路,用于检测并显示悬臂梁的谐振频率。将悬臂梁传感器、接口电路和频率读出电路集成在一起,做出了小巧便携式样机,用该样机可成功探测到体积分数低至约几个10-9量级的DMMP气体。

Closed-Loop Interface and Embedded Frequency Circuit for Micro-Cantilever Sensors

A closed-loop interface and embedded frequency readout circuit for resonant micro-cantilever sensors was designed.First of all,the resonant micro-cantilever sensor and interface circuit were combined to form a closed-loop self-excited oscillation system.To enhance the frequency stability and frequency tracking capacity of the system,the frequency tracking phase lock loop(PLL)circuit with fixed phase difference was introduced,and the amplifier and phase shifter were designed to meet the conditions of the closed-loop self-excited oscillation.The system possesses frequency stability as high as ±0.1 Hz and shows excellent resonant frequency tracking performance.In addition,an embedded frequency readout circuit was specially designed,which could be used for detecting and displaying the cantilever resonant frequency.By integration of the micro-cantilever sensor,interface circuit and frequency readout circuit,a portable prototype machine with small size was completed.And this machine can be successfully used to detect dimethyl methylphosphonate(DMMP)at a precision level as high as ~10-9.