不同滤波电路的幅频特性.doc

不同滤波电路的幅频特性实验目的：通过实验分别测量高通、低通、带通、带阻滤波电路的幅频特性。实验器材： 数字拟信号发生器、模拟示波器、电容若干、电阻若干、LM741实验内容：R1一， 高通滤波电路 C2C1=0.00_Uo( t )Ui( t )R2RR0图11， 选择参数C1=C2=0.022uF,R1=R2=15K,R0=22K, R0=39K,按图1一所示连接电路图，输入端连入信号发生器，输出端连接示波器；2， 用信号发生器输入Vpp=2V的正弦波，改变频率，记录对应的输出信号的幅值记在表1中； 二， 低通滤波电路_ Ui( t )R1R2R0RC1C2图2 Uo( t )1，选择参数C1=C2=0.01uF,R1=R2=15K,R0=50K, R0=100K,按图2一所示连接电路图，输入端连入信号发生器，输出端连接示波器；2， 用信号发生器输入Vpp=2V的正弦波，改变频率，记录对应的输出信号的幅值记在表2中；三， 带通滤波电路_Ui( t )R1R2R0RC1C2R3 Uo( t )图31，选择参数R1=R3=15K,R2=30K;C1=C2=0.047uF,R0=56K; R=82K按图3所示连接电路图，输入端连入信号发生器，输出端连接示波器；2，用信号发生器输入Vpp=2V的正弦波，改变频率，记录对应的输出信号的幅值记在表3中；四，带阻滤波电路_Ui( t )Uo( t )RRR0RCC2CR/2图4 1，选择参数R=15K，C2=0.022uF，C=0.1Uf,R0=120K,R=150K,按图4所示连接电路图，输入端连入信号发生器，输出端连接示波器；2，用信号发生器输入Vpp=2V的正弦波，改变频率，记录对应的输出信号的幅值记在表4中；*（测量幅频特性曲线前，先大致改变频率，观察输出幅值的变化，记下最大幅值，并计算出截止频率对应的幅值，在改变频率时在截止频率附近密集取值）实验数据及分析：一， 高通滤波电路理论结果：因为： 所以：（1）放大倍数：Au=1+R0R=1+22391.56（2）截止频率：fc=12R1R2C1C2482Hz500Hz实验结果：表1f(Hz)1050100150200250300350400420440A(f)/v0.05680.02900.08000.1620.2720.4260.5740.7700.9200.9851.05f(Hz)460470475480490500520540560580600A(f)/v1.101.121.141.151.181.201.241.281.311.341.36f(Hz)620640660680700720740760780800820A(f)/v1.401.431.451.471.491.491.501.531.541.541.54f(Hz)8408608809009209409609801K1.5K2KA(f)/v1.561.561.561.591.601.601.601.621.621.621.62所以:放大倍数Au=1.62 截止频率fc=480Hz(当A=0.707*1.62=1.15)二， 低通滤波电路理论结果：因为： 所以：1，带内增益：Au=1+R0R=1+51100=1.512，截止频率：fc=12R1R2C1C21061Hz1KHz实验结果：表2f (Hz)10305090110120130140150170190210230250A(f)/v1.331.581.581.601.601.601.601.581.581.581.581.581.581.58f (Hz)270290310330350370380390410420450470480510A(f)/v1.581.581.581.581.581.581.581.571.571.561.551.551.551.53f (Hz)5605806106306406606807008009009509609801000A(f)/v1.511.501.481.461.451.431.421.321.221.181.171.161.141.13f (KHz)1.021.051.11.21.31.41.51.61.71.81.92.02.12.2A(f)/v1.121.101.051.050.860.780.720.650.590.560.510.460.440.37f (KHz)2.32.42.52.62.72.82.93.04.05.0100A(f)/v0.340.320.290.270.260.240.230.220.130.0780.018所以:放大倍数Au=1.60 截止频率fc=1KHz (当A=0.707*1.6=1.13)三，带通滤波电路理论结果：因为： 所以：1，放大倍数：Au=1+R0R=1+56821.682,带通中心频率：fc=12CR1+R3R1R2R3200Hz实验结果：表3f(Hz)15101214182024282929.5A(f)/v00.220.530.6260.831.0351.121.281.351.391.4f(Hz)3031344044485054586266A(f)/v1.411.431.51.71.771.811.871.911.9722.02f(Hz)7686106116119124128136144148156A(f)/v2.022.022.022.0221.971.941.911.861.861.82f(Hz)164172178184186192198205220240245A(f)/v1.791.741.71.671.671.621.621.571.521.421.41f(Hz)2502602703004506008001K2K3K4KA(f)/v1.401.351.331.230.890.70.530.4380.2440.1820.146f(Hz)5K6K8K10KA(f)/v0.1260.110.0650.056所以:放大倍数Au=2.02 截止频率fl=31Hz,fh=240Hz (当A=0.707*2.02=1.43) 四，带阻滤波电路：理论结果： 因为： 所以：1，放大倍数：Au=1+R0R1=1+120150=1.82，中心频率：fc=12CR50Hz实验结果：表4f(Hz)512151720232628293031A(f)/v1.921.891.871.841.791.761.711.631.61.61.52f(Hz)3334353636.5373839404142A(f)/v1.521.451.421.361.351.341.281.241.171.131.05f(Hz)4344454647484950515253A(f)/v0.980.930.840.760.710.60.420.3440.2730.2320.25f(Hz)5455565758596061626364A(f)/v0.3260.410.5140.6160.810.9111.081.171.231.3f(Hz)64.164.264.364.464.5666768697071A(f)/v1.311.331.331.331.361.421.471.521.581.61