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1、摘要实际上，语音信号在输出时总是不可避免的受到身边环境噪声干扰，和信号接收时电子装置等也会产生噪声干扰。为了能得到原始的语音信号，则需要通过滤波器对受干扰的语音信号进行噪声滤除。针对于多频干扰的语音信号的噪声滤除进行有源低通滤波器设计,使语音信号频率低于截止频率的能完全通过，大于截止频率的将迅速衰减或抑制为零，从而达到噪声信号的过滤，得到原始的语音信号。首先论述了语音信号的特点和滤波器的基本原理，分析了低通、高通、带通及带阻滤波器的工作原理，并对无源滤波器和有源滤波器进行分析和比较，从而确定滤波器设计选用有源低通滤波器；然后重点地分析了巴特沃斯、切比雪夫和贝塞尔有源低通滤波器各自的特性和
2、优缺点，同时分析了各阶有源低通滤波器基于巴特沃思响应逼近的传递函数，在此基础上,设计了具有压控电压源型电路结构的五阶巴特沃思有源低通滤波器；接着根据滤波器的性能参数及截止频率,选定电容标称值,根据公式得出相应电容值及电阻值，完成滤波电路设计；最后用Multisim10.0对设计的有源低通滤波器进行仿真分析和用Matlab7.0软件对仿真结果进行理论分析和验证。仿真和验证结果表明，该有源低通滤波器在噪声过滤具有良好的效果。关键词:语音信号；滤波器；巴特沃思有源低通滤波器；传递函数ABSTRACTInfact,thespeechsignaloutputisalwaysunavoidablee
3、nvironmentalnoiseinterferencebyside,andwhenreceivingsignal,electronicdevicesalsocanproducenoiseinterference.Inordertogettheoriginalspeechsignal,youneedtofilterthespeechsignalofinterferencewithafilter.Formulti-frequencyinterferenceinthespeechsignalnoisefilteringforactivelow-passfilterdesign,thespe
4、echsignalatfrequenciesbelowthecutofffrequencycanbefullyadopted，andgreaterthanthecutofffrequencywilldecayorinhibitrapidlytozero,soastoachievenoisesignalfiltering,gettingtheoriginalspeechsignal.Firstly,itdiscussesthecharacteristicsofspeechsignalandthebasicprinciplesoffilter,analyzesworkingprinciple
5、ofthelowpass,highpass,bandpassandbandstopfilter,andthepassivefiltersandactivefiltersareanalyzedandcomparedtodeterminetouseactivelow-passfilterinthefilterdesign.ThenitanalyzesthefocusofButterworth,Chebyshev,andBesselactivelow-passfiltercharacteristicsandadvantagesanddisadvantagesofeach,andanalyzes
6、thetransferfunctionoftheorderactivelow-passfilterbasedonButterworthresponseapproximation.Onthisbasis,youdesignacircuitwithavoltage-controlledvoltagesourcetypeofthestructureoffifth-orderButterworthactivelow-passfilter.Thenaccordingtothefilterperformanceparametersandcut-offfrequency,selectsthenomin
7、alvalueofthecapacitor,accordingtotheformulatodrawthecorrespondingofcapacitanceandresistancevaluestocompletethefiltercircuitdesign.Finally,theactivelow-passfiltergetssimulationanalysiswithMultisim10.0,andgetstheoretical
