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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。
The resonant micro-cantilever sensor closed-loop interface and embedded frequency readout circuit are designed. First, the resonant micro-cantilever sensor and interface circuit form a closed-loop self-oscillation system. In order to improve the frequency stability and frequency tracking performance of the closed-loop system, a phase-locked loop circuit with no phase difference frequency tracking is introduced, and an amplifier phase-shift circuit is designed to satisfy the closed-loop self-oscillation condition. The frequency stability of the closed-loop system up to ± 0.1Hz, and can track changes in cantilever resonant frequency in real time. In addition, an embedded frequency readout circuit is designed to detect and display the cantilever resonant frequency. Integrating the cantilever sensor, the interface circuit and the frequency readout circuit, a compact and portable prototype was successfully used to successfully detect DMMP gas with a volume fraction as low as about 10-9.