摘要QCM是一种新型的高灵敏度的微质量传感器，被广泛应用于生物、环境科学、分析化学、医学等领域中。然而由于它输出的有用的信号较弱，谐振幅度很小，因此很容易湮没在高频输出的噪声中，这无疑就给QCM信号的正确采集增添了难度。本文针对微弱信号难采集这一情况设计了一种基于相关性原理的QCM信号采集电路。
本论文在探讨了 QCM 等效电路和它的采集测量原理的基础上，分析了QCM信号采集的各种方法。在综合考虑各类方法的优缺点以及在实际中的应用等因素后，最终提出了基于相关性原理的QCM信号采集的电路设计。该电路先通过以基于AD9835芯片的DDS信号发生器产生频率持续可变的余弦信号，来驱动QCM振动，之后通过基于AD985的电荷放大电路将微弱信号放大，其中还设计一种双谐振QCM的电路改善测量时的误差，接着设计了基于AD7710芯片的A/D转换电路将电信号转化为数字信号，最后将设计好的电路图进行PCB设计。19573
关键词：  QCM；信号采集；频谱分析；DDS信号发生器
毕业设计说明书（论文）外文摘要
Title  The design of QCM hardware circuit of sensor signal acquisition system                                  
Abstract
QCM is a new type of highly precise micro-mass sensor . Due to the QCM design resonance amplitude is small (nanometer level),and the signal is weak.So the useful signal is submerged in the signal of high frequency output, it is more difficult  to receipt the QCM design signal correctly. In this paper, according to the situation of weak signal acquisition design of a QCM signal acquisition circuit based on the principle of relevance.
Investigated the QCM equivalent circuit and the measuring principle, then analyze a variety of the QCM signal acquisition methods. Taking into account comprehensively including the pros and cons of the various types of methods and practical applications, and other factors. Finally, the circuit design of QCM signal acquisition based on the principle of relevance. The circuit through the first generation of cosine signal frequency continuous variable to the DDS signal generator based on AD9835 chip, to drive the QCM vibration, followed by the AD985 charge amplifier circuit based on the weak signal amplification circuit, which also designed a double resonant QCM improve the measurement error, then designed based on AD7710 chip A/D conversion circuit converts the signals into digital signals, the circuit design of PCB design.
Keywords   QCM;Signal acquisition;Spectrum analysis; DDS signal generator.
目录
1 绪论    1
1.1引言    1
1.2 QCM概述    1
1.3国内外研究现状    2
1.4本文主要工作    2
2 QCM的基本工作原理    4
2.1 QCM的压电特性    4
2.2 QCM传感器的等效电路    4
2.3 QCM测量原理    7
3 QCM信号采集方法分析    8
3.1 耗散因子法    8
3.2 频谱分析法    9
3.3 锁相振荡电路法    9
3.4 普通振荡电路法    10
3.5 QCM 信号采集方法的选取    12
4  信号采集系统硬件电路设计    13
4.1  DDS信号发生器的设计    13
4.2  具有参考电阻的信号采集系统电路设计    15
4.3  双谐振QCM的设计    20
4.5  A/D转换电路    23
4.6 PCB制图    25
4.7 本章小结    27 QCM传感器信号采集系统硬件电路的设计+PCB电路图:http://www.751com.cn/zidonghua/lunwen_10990.html