科技英语 4低通滤波器 原文与翻译

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1、WordsandExpressions9integratorn.积分器amplituden.幅值slopen斜率denominatorn.分母impedancen阻抗inductorn.电感capacitorn电容cascaden.串联passbandn通带ringingn.振铃dampingn.阻尼，衰减conjugateadj.共轭的stagev.成为9low-passfilters低通滤波器buildingblock模块linearramp线性斜坡log/logcoordinates对数/对数坐标Bod

2、eplot伯德图transferfunction传递函数complex-frequencyvariable复变量complexfrequencyplane复平面realcomponent实部frequencyresponse频率响应complexfunction复变函数Laplacetransform拉普拉斯变换realpart实部imaginarypart虚部angularfrequency角频率frequencyresponse频率响应transientresponse瞬态响应decaying-expon

3、entialresponse衰减指数响应stepfunctioninput阶跃（函数）输入timeconstant时间常数first-orderfilters一阶滤波器second-orderlow-passfilters二阶低通滤波器passivecircuit无源电路activecircuit有源电路characteristicfrequency特征频率qualityfactorn.品质因子，品质因数circularpath圆弧路径complexconjugatepairs共轭复数对switched-ca

4、pacitor开关电容9negative-realhalfofthecomplexplane复平面负半平面9Unit4Low-passFiltersFirst-OrderFiltersAnintegrator(Figure2.la)isthesimplestfiltermathematically,anditformsthebuildingblockformostmodernintegratedfilters.Considerwhatweknowintuitivelyaboutanintegrator.Ify

5、ouapplyaDCsignalattheinput(i.e.,zerofrequency),theoutputwilldescribealinearrampthatgrowsinamplitudeuntillimitedbythepowersupplies.Ignoringthatlimitation,theresponseofanintegratoratzerofrequencyisinfinite,whichmeansthatithasapoleatzerofrequency.(Apoleexistsa

6、tanyfrequencyforwhichthetransferfunction'svaluebecomesinfinite.)（为什么为极点，为什么低通？）Figure2.laAsimpleRCintegratorWealsoknowthattheintegrator'sgaindiminisheswithincreasingfrequencyandthatathighfrequenciestheoutputvoltagebecomesvirtuallyzero.Gainisinverselyproport

7、ionaltofrequency,soithasaslopeof-1whenplottedonlog/logcoordinates(i.e.,-20dB/decadeonaBodeplot,Figure2.1b).Figure2.1bABodeplotofasimpleintegratorYoucaneasilyderivethetransferfunctionasWheresisthecomplex-frequencyvariableandis1/RC.Ifwethinkofsasfrequency,thi

8、sformulaconfirmstheintuitivefeelingthatgainisinverselyproportionaltofrequency.9Thenextmostcomplexfilteristhesimplelow-passRCtype(Figure2.2a).Itscharacteristic(transferfunction)isWhen,thefunctionreduces