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带阻滤波器设计原理计算时间2009-07-0820:38:37 来源资料室 作者滤波器是一种只传输指定频段信号,抑制其它频段信号的电路 滤波器分为无源滤波器与有源滤波器两种
①无源滤波器: 由电感L、电容C及电阻R等无源元件组成
②有源滤波器: 一般由集成运放与RC网络构成,它具有体积小、性能稳定等优点,同时,由于集成运放的增益和输入阻抗都很高,输出阻抗很低,故有源滤波器还兼有放大与缓冲作用利用有源滤波器可以突出有用频率的信号,衰减无用频率的信号,抑制干扰和噪声,以达到提高信噪比或选频的目的,因而有源滤波器被广泛应用于通信、测量及控制技术中的小信号处理从功能来上有源滤波器分为 低通滤波器(LPF)、高通滤波器(HPF)、 带通滤波器(BPF)、带阻滤波器(BEF)、 全通滤波器(APF)其中前四种滤波器间互有联系,LPF与HPF间互为对偶关系当LPF的通带截止频率高于HPF的通带截止频率时,将LPF与HPF相串联,就构成了BPF,而LPF与HPF并联,就构成BEF在实用电子电路中,还可能同时采用几种不同型式的滤波电路滤波电路的主要性能指标有通带电压放大倍数AVP、通带截止频率fP及阻尼系数Q等带阻滤波器(BEF)如图1(a)所示,这种电路的性能和带通滤波器相反,即在规定的频带内,信号不能通过(或受到很大衰减或抑制),而在其余频率范围,信号则能顺利通过在双T网络后加一级同相比例运算电路就构成了基本的二阶有源BEFHYPERLINKhttp://www.838dz.com/d/file/danyuan/lvbo/2009-07-08/1fd1f58d4829963da1c0ec1c7448c6c
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4.jpg\*MERGEFORMAT a电路图 b频率特性 图1二阶带阻滤波器电路性能参数:通带增益 HYPERLINKhttp://www.838dz.com/d/file/danyuan/lvbo/2009-07-08/5cde4fbc5320de062d4988fed38b
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38.gif\*MERGEFORMAT 带阻宽度B=2(2-Aup)f0选择性HYPERLINKhttp://www.838dz.com/d/file/danyuan/lvbo/2009-07-08/ea7244e737a9b4e37f76ca7c897119dd.gif\t_blankINCLUDEPICTUREhttp://www.838dz.com/d/file/danyuan/lvbo/2009-07-08/ea7244e737a9b4e37f76ca7c897119dd.gif\*MERGEFORMAT 1.压控电压源二阶带阻滤波器电路如图2所示电路的传输函数HYPERLINKhttp://www.838dz.com/d/file/danyuan/lvbo/2009-07-08/4d2c7532e8f4ad897b7e242bdb953a6e.gif\t_blankINCLUDEPICTUREhttp://www.838dz.com/d/file/danyuan/lvbo/2009-07-08/4d2c7532e8f4ad897b7e242bdb953a6e.gif\*MERGEFORMATHYPERLINKhttp://www.838dz.com/d/file/danyuan/lvbo/2009-07-08/b22b1b4c5f463dc0cf95fd342e3ff37a.gif\t_blankINCLUDEPICTUREhttp://www.838dz.com/d/file/danyuan/lvbo/2009-07-08/b22b1b4c5f463dc0cf95fd342e3ff37a.gif\*MERGEFORMAT其中,通带电压放大倍数HYPERLINKhttp://www.838dz.com/d/file/danyuan/lvbo/2009-07-08/da3cf9603b37888fbd36bfce844ad8c
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2.无限增益多路负反馈二阶带阻滤波器该电路由二阶带通滤波器和一个加法器组成,如图3所示电路的传输函数为HYPERLINKhttp://www.838dz.com/d/file/danyuan/lvbo/2009-07-08/f83912416711a1551afb8276e61b1d
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8.gif\*MERGEFORMAT设计步骤1)选用附录中图2电路2)该电路的传递函数HYPERLINKhttp://www.838dz.com/d/file/danyuan/lvbo/2009-07-08/25625575ee6ae7ecde6ffb9a
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80.jpg\*MERGEFORMAT图2压控电压源二阶带阻滤波器HYPERLINKhttp://www.838dz.com/d/file/danyuan/lvbo/2009-07-08/4305f2dd52518238a01144391aa260bd.jpg\t_blankINCLUDEPICTUREhttp://www.838dz.com/d/file/danyuan/lvbo/2009-07-08/4305f2dd52518238a01144391aa260bd.jpg\*MERGEFORMAT 图3无限增益多路负反馈二阶带阻滤波器。