pspice PSpice_ch5

PSPICE计算机仿真 SimulationProgramwithIntegratedCircuitEmphasis CH5 OPERATIONALAMPLIFIER运算放大器 5 1ModelingOPAmpswithResistorsandDependentSources HowtousePSpicetoanalyzeacircuitcontaininganoperationalamplifier Fig 53 Example7 TheparametersfortheoperationalamplifierinthecircuitshowninFig 53areRi 200k A 10E4 andRo 5k 1 UsePSpicetofindViandVowhenVg 1V dc 2 ComparethePSpicesolutionwiththeanalyticsolutionforViandVo 预备知识 Anequivalentcircuitforanoperationalamplifier Fig 52 Fig 52ex7 pre ddb Solution Analoglib R E VCVS Sourcelib VDC Fig 54ex7 sch Fig 55outputfile 1 Weusedsimplebiaspointanalysis therefore V in 0 0028V 书上 0 0027V V out 10 03V 书上 9 9697V Idealoperationalamplifer IfweassumethattheoperationalampliferinthecircuitshowninFig 53isideal wecanalterathePSpiceopampschematicrepresentationbymakingRiandAverylargeandRo 0 Toillustrate wemodifytheschematicinFig 54 withR2 200M A 10E8 andR4removedfromtheschematicentirely Fig 54a Fig 54a TheresultingPSpiceoutputfileafterbiaspointanalysisisshowninFig 56 ThevaluesofviandvofromthissimulationareVi v in 10E 9V 书上 100E 9V Vo v out 10V Fig 56outputfile 2 WeobtaintheanalyticsolutionforViandVobysolvingthefollowingsimultaneousnode voltageequations YoushouldverifythatthesolutionsforViandVoareVi 2 742mVVo 9 970V 5 2UsingOPAmpsLibraryModels Example8 RepeattheanalysisofthecircuitshowninFig 53 butthistimeusetheuA741modelfromthePSpicemodellibrary Solution uA741在EVAL库中 需要在PlacePart对话框 点AddLibrary 按钮 添加该元件库 Fig 57aAddEVALLibrary Fig 57bEVALPath Fig 57ex8 sch Fig 58outputfile 5 3ModifyingOPAmpModels PlacethemodeloftheuA741fromtheEvalLibraryinyourcircuitschematic Highlighttheopampcomponent selectEdit PSpiceModelfromtheCapturemenu Fig 59a Fig 59a Fig 59ModelEditor Youdefineasubcircuitbyinsertinga SUBCKTcontrolstatement SUBCKTSUBNAMEN1N2N3Youterminatethesubcircuitdescriptionbyinsertingan ENDScontrolstatement ENDS Nowwecreateanewsubcircuitbasedontheidealopamp consistingofa1M inputresistor avoltage controlledvoltagesourcewithagainof10E6 anda200 outputresistor Fig 60ModelEditorforIdealOpAmp HighlighttheIdealOpAmpcomponent SelectEdit PartfromtheCapturemenu TheresultshouldlooklikethepartshowninFig 61 Fig 61Editmodel HighlightthenewIdealOpAmpcomponent SelectEdit PropertiesfromtheCapturemenu ThemodifiedtemplateisshowninFig 62 Fig 62EditProperty example9 RepeattheanalysisofthecircuitshowninFig 53 butthistimeu