带通滤波器设计
学院
通信工程专业CDIO三级项目
项目设计说明书
(2010/2011学年第二学期)
项目名称 : 电子电路仿真 题 目 : 模拟带通滤波器的设计 专业班级 : 学生姓名 : 学 号: 指导教师 : 设计周数 :
设计成绩 :
目 录
1 模拟带通滤波器设计的目的 ·················································································· 2 1.1设计任务 ·········································································································· 2 1.2设计题目 ·········································································································· 2 1.3设计要求 ·········································································································· 2 2模拟带通滤波器的软件设计 ··················································································· 3 2.1电路图的设计方案 ·························································································· 3 2.2电路图的原理 ·································································································· 3 2.3电路的算法 ······································································································ 3 2.4电路仿真、分析 ······························································································ 4 3模拟带通滤波器的硬件设计 ··················································································· 6 3.1电路元器件清单 ······························································································ 6 3.2焊接电路 ·········································································································· 6 3.3电路的调试 ······································································································ 7 4模拟带通滤波器的设计总结 ··················································································· 7 5设计的心得体会 ······································································································· 7
参考文献 ······················································································································ 8
1 模拟带通滤波器设计的目的
设计滤波器的主要目的就是理论结合实际,锻炼大学生将已学的知识综合应用,并提高学生的动手能力。设计有源带通滤波器,首先要了解无源高、低通滤波器的原理,然后连接运算放大器构成有源带通滤波器。 1.1设计任务
1) 查阅相关资料,了解滤波器的工作原理、分类、以及在通信系统的应用; 2) 进行功能分析,给出设计方案; 3) 熟悉所用器件的功能特性;
4) 设计电路原理图,并给出详细的设计过程;
5) 进行硬件制作及EWB或Multisim仿真软件进行仿真; 6) 进行调试,实现技术要求; 7) 编写设计报告。 1.2设计题目
压控电压源二阶有源带通滤波器设计 1.3设计要求
1) 掌握有源滤波器和无源滤波器设计方法和过程;
2) 要求设计一个有源二阶带通滤波器,指标为:通带中心频率为500Hz,通带中心频率处的
电压放大倍数为10; 3) 带宽为50Hz;
4) 对其设计电路进行仿真并利用相应元件搭建电路; 5) 结合现有仪器仪表进行系统调试; 6) 掌握理论联系实践的方法。
2模拟带通滤波器的软件设计 2.1电路图的设计方案
2.2电路图的原理
这种滤波器的作用是只允许在某一个通频带范围内的信号通过,而比通频带下限频率低和比上限频率高的信号均加以衰减或抑制。典型的带通滤波器可以从二阶低通滤波器中将其中一级改成高通而成。再连接一个运算放大器,就构成了有源二阶的带通滤波器。 2.3电路的算法
电路的传递函数:
图2.1
压控电压源二阶带通滤波
Avs
Avos2
0
sQ
02
s0Q
带通滤波器的中心角频率为:
品质因数:
0
111
R3C2RR21
Q
f0f0
BWf
频带增益:
AR5f1
R
4
中心角频率处电压放大倍数:
Af
vo
AR1 R11A1
1f1R2
R
3
品质因数:
Q
0
12
C11
R1Af
3R1R2
2.4电路仿真、分析
有图2.4(a)在workbench软件中作出电路图:
图2.4(a) 压控电压源二阶带通滤波器EWB仿真连线
输入计算的参数值,得到图2.4(b)压控电压源二阶带通滤波 器的幅频特性曲线,可以找到电路的中心截止频率
在幅频特性曲线上可以找到滤波器的带宽BW,有公式20lg0.7073dB可知,当最大截止频率对应的幅值向两侧衰减3dB时,就分别对应着他的上限截止频率和下限截止频率,
图2.4(b) 电路的幅频特性曲线
f0513z。
BWfHfL54648561Hz。
图2.4(c) 幅频特性曲线
3模拟带通滤波器的硬件设计 3.1电路元器件清单
3.2焊接电路
图3.2(a) 带通滤波器电路板正面
图3.2(b)带通滤波器电路板反面
3.3电路的调试
由于电路板是万用型的,所以焊接一定要用到导线,而且导线必须经过剥皮镀锡,在此过程中可能会出现导线内部断开,可能存在镀锡氧化而绝缘,为了排除导线的干扰,用万用表测试导线是否导通,或是否短路。
由于电阻和所标的型号有时不一致,最好先测一测阻值,检查电阻是否损坏或阻值与标称不一致。调试过程中,先看带通滤波器输出波形如何,若失真,则是硬件焊接的问题,用万用表测试几个点即可;若没有波形输出,则可能是运放没有工作或烧毁。用万用表测试运放的正想输入端3端,看是否有波形输出,若有,运放有问题,若没有,焊接有问题。 4模拟带通滤波器的设计总结
我们这组的题目是有源带通滤波器,我们选择了压控电压源二阶带通滤波器,指导书的的要求是要求设计一个有源二阶带通滤波器,通带中心频率为500Hz,通带中心频率处的电压放大倍数为10;带宽为50Hz。根据要求,选用相应的元件实现带通滤波器电路,并对进行仿真和制作,并能利用相关仪器测量其技术指标,通过示波器观察结果。我们测得的数据跟理论值有差距,但不是很大,我们最后得到截止频率为513Hz,带宽为61Hz。 5设计的心得体
这次的课程设计是进入大学以来,第一次自己设计,自己制作硬件,虽然在设计和制作过程中有种种的困难和不解,都是因为自己的努力还不够。每次有问题问指导老师,老师都会锻炼我,让我们自己查去资料,不过,老师还是会指明一个方向,该怎么做,应先从哪里着手。事实上,刚开始遇到这个设计是就一脸的茫然,不知道从哪里着手,小组人员都是如此,最后还是在指导老师的帮助下才会顺利的进行下去,以至于最后的成功。
经过这次的设计制作后,我更加懂得了理论知识的重要性,动手能力的重要性。更加明白,在使用仪器时,首先,弄明白一起怎么使用,然后在测试电路。因为在做实验过程中,连续不断的出现仪器损坏的情况。所以,要学会使用仪器。培养我们的实际动手能力、理论联系实践的能力。通过这次的课程设计让我们掌握电子电路系统的设计、制作、调试、仿真的方法。
参考文献
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