RC振荡电路设计报告

RC振荡电路设计姓名学号院、系、部班号完成时间※※※※※※※※※※※※※※※※※※※※※※※※2013级模拟电子技术课程设计摘要RC振荡电路一般由放大电路，反馈网络，选频网络和稳幅环节四个部分组成。它适用于低频振荡，一般产生几赫~几百千赫的低频信号。RC振荡电路中，放大电路和反馈网络构成正反馈系统，共同满足正弦波振荡条件。选频网络的作用是实现单一频率的正弦波振荡。另外，有了稳幅环节就可以使振荡幅度达到稳定。本设计主要采用文氏电桥振荡电路连接示波器构成正弦波发生器。通过按RC振荡电路组成部分计算参数设计仿真电路，焊接电路板，实现振荡频率为160Hz的正弦波发生器实物。RC振荡电路有许多种形式，常用的RC振荡电路有文氏电桥振荡电路，移相式振荡电路和双T型选频网络振荡电路等。但除了文氏电桥振荡电路，其它RC振荡电路的应用并不广泛。本设计按指标要求选用具有成本低、性能指标高、可靠、使用简单、安装调试方便等优点的文氏电桥振荡电路设计频率为160Hz的正弦波发生器。关键词：RC振荡电路文氏电桥振荡电路稳幅正弦波发生器目录第1章设计任务与要求···························································································4第2章方案与论证·································································································42.1RC振荡电路组成···························································································42.2放大电路······································································································22.3反馈网络······································································································22.4选频网络······································································································22.5稳幅环节······································································································32.6正弦波发生器································································································3第3章单元电路设计与参数计算···············································································33.1振荡频率······································································································33.2起振条件······································································································33.3选择集成运放放大器·······················································································33.4选择二极管···································································································43.5示波器·········································································································4第4章仿真与调试·································································································4第5章结论与心得·································································································6附录······················································································································7参考文献················································································································7RCπ21第1章设计任务与要求利用文氏桥设计一振荡频率约为160Hz的正弦波发生器。第2章方案与论证RC振荡电路设计思路：(1)要使得振荡频率约为160Hz，应根据RC振荡电路振荡频率公式f=来选取合适的R和C的值以实现单一频率的正弦波振荡。(2)根据选取的R和C元件组成RC串并联网络。选择合适的集成运放芯片作为放大电路，再连入反馈网络，使反馈网络和放大电路构成正反馈系统。另外还要在RF和R’支路引入一个负反馈。连接RC串并联网络，放大电路和反馈网络组成文氏电桥振荡电路。并且，RF和R’之间还要满足RC振荡电路的起振条件。(3)文氏电桥振荡电路组成好以后，在反馈电阻R串联一个并联两个方向相反的二极管的支路实现RC振荡电路的稳幅。(4)在文氏电桥振荡电路的输出端连接示波器，即可得到振荡频率约为160Hz的正弦波发生器。2.1RC振荡电路组成RC振荡电路由放大电路，反馈网络，选频网络和稳幅环节组成。RC振荡电路的原理图如图所示。图2-1RC振荡电路原理图22.2放大电路RC振荡电路中的放大电路由集成运放放大器构成。放大电路可以实现对信号的放大，并且放大电路会和反馈网络构成正反馈网络，在RC振荡电路中具有重要的实际作用。2.3反馈网络RC振荡电路中，连接集成运放和RC串并联电路，在RC串联电路和RC并联电路的接线处连接一根导线至集成运放的正极，就可以得到一个接成正反馈的反馈网络。另外，RF和R’支路还引入一个负反馈。反馈网络原理如图2-3所示。图2-3RC振荡电路反馈网络原理2.4选频网络RC振荡电路的选频网络是RC串并联网络，由电阻和电容元件构成。电路图如图2-4所示。3图2-4RC振荡电路的选频网络2.5稳幅环节为了使振荡幅度达到稳定，可以使用两个方向相反的二极管并联再串联反馈电阻RF，以达到稳幅的作用。2.6正弦波发生器在RC振荡电路的输出端连接示波器就可以得到规定频率的正弦波发生器。第3章单元电路设计与参数计算3.1振荡频率题目要求RC振荡电路的频率约为160Hz。根据RC振荡电路振荡频率的计算公式：f=计算合适的R和C的参数。选取参数为10kΩ的电阻，0.01uF的电容。3.2起振条件RC振荡电路的振荡条件为|A·F·|=1，即满足幅值平衡条件和相位平衡条件。幅值平衡条件为A··F·=1，相位平衡条件为φa+φf=2nπ。在f=f0=1/（2πRC）时，|F·|=1/3。所以RC振荡电路的起振条件为|A·u|3。已知同相比例运算电路输出电压与输入电压之间的比例系数为1+RF/R’，为了达到1+RF/R’3，负反馈支路的参数应满足的关系为RF2R’。若参数选择不适当则容易使波形失真。故选择10k的电位器以改变RF，R’=2.1kΩ。3.3选择集成运放要选择增益大且适合RC振荡电路的集成运放，所以选择型号为UA741CN的集成运放放大器。UA741CN的特性参数为：工作电压：22V；差分电压：30V；RCπ214输入电压：18V；UA741CN的管脚图如图3-3所示：图3-3UA741CN管脚图3.4选择二极管二极管的作用是使振荡幅度达到稳定。RC振荡电路中选用1N4007GP作为稳幅二极管。1N4007GP的主要参数为：最高反向耐压：1000V；最大正向平均整流电流：1.0A；正向压降：1.0V；3.5示波器设计好的RC振荡电路再连接一个示波器就能得到固定频率的正弦波发生器。注意示波器的通道连接了RC振荡电路的输出端以后还要接地。第4章仿真与调试根据Multisim软件绘制仿真电路图。在电路图仿真的时候，要将所需的元件连接正确，确保电路是正确的，输出波形是正确的。电路图连接好以后，双击示波器点击开始按键，观察示波器中正弦波形的产生。在电路连接正确的条件下，电路会有频率为160Hz的正弦波产生。如果在运行框中的波形运行的速度太快或者太慢，调节图形框下的timebase的比例。如果要调节波形的高度，调节所连接通道的channel的比例。知道产生速度适中，高度适中的正弦波。仿真电路完成后，根据仿真电路图进行电路板焊接。焊接时，先固定原件，再焊5接导线。安装元件的时候，按电路的组成部分一部分一部分安装。所以先安装RC串并联电路，再连接放大电路和反馈网络，最后再用反馈电阻RF串联一个两个并连着的反向的二极管以实现稳幅作用。安装时要注意，注意两个二极管连接的时候极性要相反。元件安装完成后，再焊接导线将电路完善。具体的仿真调试图如下图4-1所示。图4-1RC振荡电路构成的正弦波发生器仿真调试图6图4-2RC振荡电路构成的正弦波发生器波形7图4-3RC振荡电路实物第5章结论与心得经过近几天的努力，终于完成了RC振荡电路的课程设计。在设计的过程中，因为电路的连接方式，电路的具体原理和电路板的焊接等问题烦恼过，但也因为最后成功解决了这些问题而欣喜。要完成课题设计首先要有一个可以实现课题要求的电路图。Multisim仿真软件对我们在设计电路图和检查电路结果方面有很好的帮助。但是，不能快速且熟练的使用仿真软件是我们的一大难题。所以，我们应该在课外时间多熟悉和学习应用仿真软件，它会在我们学习专业知识时提供很大的帮助。在焊接电路板的过程中，由于是第一次焊接电路板，焊接的技术和手法还非常的生疏。焊接电路板的时候，要先用焊锡固定住元件，将元件在电路板上按照电路图上的位置摆放。固定好元件以后再用焊锡和导线连接各个元件。在电路板上摆放各个元件的时候，要看好电路板上一一对应的电路孔。不能将元件的插头插入有铜线连接的8两个孔，因为有铜线连接的两个孔其实是一个孔。在用焊锡焊接电路板时，要使焊锡饱满均匀且整洁的焊住元件的各个管脚，不能出现焊锡溢出到别的元件的插孔处，因为那样的话元件之间会形成连通，会直接影响到电路板的最终输出结果。而且，在焊接集成运放芯片的时候，一定要提前查好集成运放芯片的管脚图，在正确的管脚接正确的线，否则很有可能会烧坏电路板，不能完成实验。在做RC振荡的课程设计过程中，我发现我们平时所学的理论有的时候应用不到实际中去。虽然课程设计完成，但是我觉得我们真的应该多加强我们的动手能力。并且要养成在做实验的时候的好习惯。比如在连接线路之前先检查元器件的好坏，检查导线的好坏，确保接线正确再打开电源等等。通过这次的课程设