模电课程设计-三角波正弦波变换设计

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1、目录1．设计要求···································································22．总体方案···································································23．设计原理···································································33.1总体电路图···························································

2、··33.1.1硬件电路分析·····················································33.1.2差分式放大电路···················································43.1.3镜像恒流源电路···················································43.2设计所用软件简介·······················································51．原理分析与计算···················

3、··········································52．电路的仿真分析及结果·······················································63．实物连接与调试结果·························································84．此次设计过程中所遇到的问题及解决措施······································115．设计的心得体会··········································

4、··················126．参考文献··································································121.1.设计要求在研制、生产、使用、测试和维修各种电子元器件、部件以及整机设备时，都需要有信号源，由它产生不同频率、不同波形的电压、电流信号并加到被测器件、设备上，用其他测量仪器观察、测量被测者的输出响应，以分析和确定它们的性能参数。而波形发生器是它们中一种更为常用的信号源，广泛地应用于电子电路、自动控制系统和教学实验等领域。本次课程设计应用所学电路设计构成可由生三角波变换为正弦波。可根据需

5、要对该正弦波进行利用或者是进一步处理。在本设计方案中，三角波——正弦波的变换电路主要由差分式放大器来完成。差分式放大电路的工作点稳定，输入阻抗高，抗干扰能力强，可以有效的抑制零点漂移。利用差分放大器可将低频的三角波转换成正弦波。波形变换是利用差分放大电路的非线性特性。2.总体方案三角波—正弦波变换设计有以下两种种方案：1)由三角波的傅里叶级数可知，它含有基波和3、5次等基次谐波，因此可以通过低通滤波器除去基波，滤出高次谐波，可将三角波转换为正弦波。三角波低通滤波电路正弦波图2—12)三角波——正弦波变换电路课采用非线性有源电路形成法即利用差分式放大电路来实现。三角波差分放大电

6、路正弦波图2—2输入电压和输出电压波形如图2—3所示：第16页共18页图2—3上述方案的优缺点：优点：对于方案一所需元器件少，节约了成本，更重要的是利于焊接和调试；对于方案二可适用于不同频率条件，正好弥补了方案一的缺点。缺点：方案一只适合固定频率或者频率变化很小的场合；方案二中所需元件较多，焊接与调试有一定难度。此次设计我采用方案二，利用BJT射极耦合差分放大电路的单端输入和单端输出和BJT镜像电流源来实现。3.设计原理3.1总体电路图第16页共18页图3—13.1.1硬件电路分析分析表明，传输特性曲线的表达式为：式中;为差分放大器的恒定电流；为温度的电压当量，当室温为时。根

7、据理论分析，如果差分式电路的差模输入信号为三角波，则与的波形近似为正弦波。因此，单端输出电压也近似于正弦波，从而实现三角波—正弦波的变换。且差分式放大电路传输特性曲线的线性区越窄，其输出波形越接近于正弦波。如图3—1所示得电路中，用于调节电路的对称性，使得差分式放大电路的传输特性的线性区变窄。电容、分别为隔直电容和滤波电容，以消除谐波分量，改善输出波形。3.1.2差分式放大电路第16页共18页图3—2此次设计中，差分式放大电路采用单端输入—单端输出的电路形式，实际电路中四只晶体管选用集成电路的差分对称管