《学科竞赛ch》ppt课件

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1、Ch6BasicBJTAmplifiers6.1.1GraphicalAnalysis6.1.2Small-SignalModelAnalysis6.1.3Common-EmitterAmplifiers6.1ACAnalysisofTransistorCircuits6.1ACAnalysisofTransistorCircuits(CH4)AnalogSignalsAsignalcontainssometypeofinformation.Therearetwokindsofsignals:analoganddigital

2、.Analogsignal,suchastemperature,pressure,velocity,cantakeonanyvalueandmayvarycontinuouslywithtime.Themagnitudeofdigitalsignalhasafinitenumberofdigitsataninstantoftime,andnolongerisacontinuousfunctionoftime.Electroniccircuitsthatprocessanalogsignalsarecalledanalogci

3、rcuit.6.1.1GraphicalAnalysis1.ACandDCValuesCommon-emittercircuitWeaddasinusoidalsignalsourceinserieswiththedcsource.vsproducesacvbesuperimposedonVBE,sovBE=VBE+vbeiB=IB+ibiC=IC+icvCE=VCE+vce(1)Common-EmitterCircuit6.1.1GraphicalAnalysis1.ACandDCValues6.1.1GraphicalA

4、nalysis1.ACandDCValuesConclusions:1.vivBEiBiCvCE

5、-vo

6、2.Phasesofvoandviareopposite__inverter.3.Gettingvoltagegain.4.Determiningthemaxofvo.#Whenthecircuitisoperating，aretherealdirectionsofiBandiCchanging,andrealvoltagepolarityofvCEischanging？6.1.1Graphical

7、Analysis2.ACLoadLinevce=-ic(Rc//RL)Fromacequivalentcircuit,wegetDuetovce=vCE-VCEQic=iC-ICQandassumeRL=Rc//RLso,vCE-VCEQ=-(iC-ICQ)RLThatisiC=(-1/RL)vCE+(1/RL)VCEQ+ICQTheacanddcloadlinesaredifferent.TheacloadlinemustpassthroughtheQ-point,anditsslopeis-1/RL,so

8、weplottheaclineshowninfig.6.1.1GraphicalAnalysis2.ACLoadLine6.1.1GraphicalAnalysis3.NonlinearDistortion非线性失真Therearethreeregionsfori-vcharacteristic.IfQ-pointisnotsuitable,therearesaturationorcut-offdistortionsoccurred.Thei-vcharacteristicofnpn6.1.1GraphicalAnalysi

9、s3.NonlinearDistortionQ-pointislow,orvsistoolarge,cut-offdistortionoccurs.6.1.1GraphicalAnalysisQ-pointishigh,orvsistoolarge,saturationdistortionoccurs.Conclusions:Q-pointmustbesuitable.2.vsissmallenoughtoyieldlinearrelation.3.MaxsymmetricalswingcanbedeterminedIfwe

10、wantgetthemaxrangeofvO,wemust:setQ-pointatthemiddleofactiveregion,havesuitableacloadline,3.NonlinearDistortion6.1.1GraphicalAnalysisTherangeofvO3