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ID:249096
大小:4.11 MB
页数:99页
时间:2017-07-14
《网络电视业务实现方案研究 - 上海交通大学电工电子 …》由会员上传分享,免费在线阅读,更多相关内容在教育资源-天天文库。
1、Chapter6DifferentialandMultistageAmplifiersIntroduction6.1TheBJTdifferntialpair6.2Small-signaloperationoftheBJTdifferentialamplifier6.3Othernonidealcharacteristicsofthedifferentialamplifier6.4MOSdiffenrentialamplifiers6.5Biasinginintergratedcircuits6.6TheB
2、JTdifferentialamplifierwithactiveload6.9MultistageamplifiersIntroductionThedifferentialamplifier(pair)configurationisthemostwidelyusedbuildingblockinanalogICdesign.BJTdifferentialamplifieristhebasisofavery-high-speedlogiccircuitfamily,calledemitter-coupled
3、logic(ECL).Why?Reasons:DirectcouplingbetweensignalsourceandamplifierwilleasilycausetemperatureDrift(zerodrift).Whatshallwedo?AdvantagesThereare2reasonsforusingdifferentialinpreferencetosingle-endedamplifiers.(1)Differentialcircuitsaremuchlesssensitivetonoi
4、seandinterferencethansingle-endedcircuits.(2)ItenablesustobiastheamplifierandtocoupleamplifierstagewithouttheneedofbypassandcouplingcapacitorswhichareimpossibletofabricateeconomicallybyICtechnology.6.1TheBJTDifferentialPairBasicOperation-1:Common-modeinput
5、Thedifferentialpairwithacommon-modeinputsignalvCM.Twotransistorsarematched.Currentsourcewithinfiniteoutputresistance.CurrentIdivideequallybetweentwotransistors.Thedifferenceinvoltagebetweenthetwocollectoriszero.Thedifferentialpairrejectsthecommon-modeinput
6、signalaslongastwotransistorsremaininactiveregion.BasicOperation-2Thedifferentialpairwitha“large”differentialinputsignal.Q1isonandQ2isoff.CurrentIentirelyflowsinQ1.BasicOperation-3Thedifferentialpairwithalargedifferentialinputsignalofpolarityoppositetothati
7、n(b).Q2isonandQ1isoff.CurrentIentirelyflowsinQ2.BasicOperation-4:Difference-modeorDifferencesignalsThedifferentialpairwithasmalldifferentialinputsignalvi.Smallsignaloperationorlinearamplifier.AssumingthebiascurrentsourceItobeidealandthusIremainsconstantwit
8、hthechangeinvCM.IncrementinQ1anddecrementinQ2.Large-SignalOperationLarge-SignalOperationNonlinearcurves.Linearsegments.Maximumvalueofinputdifferentialvoltagesasasmall-signalamplifiercanbeusedasafastcurrentswi
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