小元件大作用：探秘半導(dǎo)體二極管Smallcomponentsplayabigimportantrole:exploringsemiconductordiodesTeacher:JiaLisi授課教師：賈麗斯前提：Premise:共射極放大電路可放大微弱信號

Common-emitteramplifiercircuitcanamplifyweaksignals放大電路要穩(wěn)定工作有哪些關(guān)鍵因素在起作用？Whatarethekeyfactorsthatplayaroleinthestableoperationoftheamplifiercircuit?靜態(tài)分析是電路穩(wěn)定工作的“地基”Staticanalysisisthe"foundation"forstablecircuitoperation解析放大電路的靜態(tài)特性AnalyzethestaticcharacteristicsoftheamplifiercircuitPart01教學(xué)目標(biāo)Teachingobjective掌握Mastery教學(xué)目標(biāo)Teachingobjective估算法、圖解法確定靜態(tài)工作點(diǎn)。Determinethequiescentoperatingpointbyestimationandgraphicalmethods理解Understanding靜態(tài)工作點(diǎn)與失真的關(guān)系。Therelationshipbetweenquiescentoperatingpointanddistortion應(yīng)用Application準(zhǔn)確計(jì)算共射極放大電路靜態(tài)工作點(diǎn)、分析失真。Accuratelycalculatethequiescentoperatingpointofthecommonemitteramplifiercircuitandanalyzethedistortion.素養(yǎng)Literacy培養(yǎng)嚴(yán)謹(jǐn)計(jì)算與精確調(diào)試能力CultivaterigorouscalculationandprecisedebuggingcapabilitiesPart02案例導(dǎo)入Caseintroduction微弱電臺信號Weakradiosignal案例導(dǎo)入Caseintroduction放大電路Amplifiercircuit正常播放Normalplayback微弱電臺信號Weakradiosignal案例導(dǎo)入Caseintroduction放大電路Amplifiercircuit靜態(tài)工作點(diǎn)不當(dāng)Improperquiescentoperatingpoint聲音嘶啞、斷續(xù)、不清hoarse,intermittent,orinaudiblesound案例導(dǎo)入Caseintroduction聲音轉(zhuǎn)化為電信號Convertsoundintoelectricalsignals案例導(dǎo)入Caseintroduction聲音轉(zhuǎn)化為電信號Convertsoundintoelectricalsignals靜態(tài)工作點(diǎn)不當(dāng)Improperquiescentoperatingpoint播放聲音異常Abnormalplaybacksound指放大電路沒有輸入信號時(shí)的工作狀態(tài)。Staticstatereferstotheoperatingstateofanamplifiercircuitwhennoinputsignalispresent.

此時(shí)，電路中只有直流電源作用Duringthisstate,onlytheDCpowersupplyisactinginthecircuit,三極管各電極的電流和電壓都是直流值。thecurrentandvoltageacrosseachtransistor'selectrodesareDCvalues.靜態(tài)StaticstatePart03靜態(tài)分析的目的Purposeofstaticanalysis確定三極管靜態(tài)工作點(diǎn)（Q點(diǎn)），參數(shù)：基極電流（Ib）、集電極電流（Ic）、集電極-發(fā)射極電壓（Uce）Todeterminethetransistor'squiescentoperatingpoint(Qpoint),parameters:basecurrent(Ib),collectorcurrent(Ic),collector-emittervoltage(Uce)目的

Purpose靜態(tài)分析的目的Purposeofstaticanalysis保證三極管始終工作在放大區(qū)，避免信號失真，支撐電路正常放大。Ensurethatthetransistoralwaysworksintheamplificationarea,avoidsignaldistortion,andsupportnormalamplificationofthecircuit.作用

FunctionPart04確定靜態(tài)工作點(diǎn)的方法

Methodfordeterminingthequiescentoperatingpoint如何確定靜態(tài)工作點(diǎn)Howtodeterminethequiescentoperatingpoint

估算法Estimationmethod圖解法Graphicalmethod確定靜態(tài)工作點(diǎn)的方法Methodfordeterminingthequiescentoperatingpoint估算法：Estimationmethod通過電路的直流通道，利用歐姆定律和三極管的電流關(guān)系來計(jì)算靜態(tài)工作點(diǎn)。UseOhm'slawandthetransistorcurrentrelationshiptocalculatethequiescentoperatingpointthroughthecircuit'sDCpath.確定靜態(tài)工作點(diǎn)的方法Methodfordeterminingthequiescentoperatingpoint斷開Opencircuit斷開Opencircuit

對直流信號，耦合電容C可看作開路

ForDCsignals,thecouplingcapacitorCcanberegardedasanopencircuit.

直流通路DCpath估算法：Estimationmethod通過電路的直流通道，利用歐姆定律和三極管的電流關(guān)系來計(jì)算靜態(tài)工作點(diǎn)。UseOhm'slawandthetransistorcurrentrelationshiptocalculatethequiescentoperatingpointthroughthecircuit'sDCpath.確定靜態(tài)工作點(diǎn)的方法Methodfordeterminingthequiescentoperatingpoint斷開Opencircuit斷開Opencircuit

對直流信號，耦合電容C可看作開路

ForDCsignals,thecouplingcapacitorCcanberegardedasanopencircuit.

直流通路DCpath估算法：Estimationmethod確定靜態(tài)工作點(diǎn)的方法Methodfordeterminingthequiescentoperatingpoint斷開Opencircuit斷開Opencircuit

對直流信號，耦合電容C可看作開路

ForDCsignals,thecouplingcapacitorCcanberegardedasanopencircuit.

直流通路DCpath步驟（分壓式偏置共射極電路）：Steps(voltagedividerbiascommonemittercircuit):算基極電位（Ub）Calculatethebasepotential(Ub)算發(fā)射極電位（Ue=Ub-Ube，硅管Ube≈0.7V，鍺管≈0.3V）Calculatetheemitterpotential(Ue=Ub-Ube,Ube≈0.7Vforsilicondiodes,0.3Vforgermaniumdiodes)算發(fā)射極電流Calculatetheemittercurrent

估算法：Estimationmethod確定靜態(tài)工作點(diǎn)的方法Methodfordeterminingthequiescentoperatingpoint斷開Opencircuit斷開Opencircuit

對直流信號，耦合電容C可看作開路

ForDCsignals,thecouplingcapacitorCcanberegardedasanopencircuit.

直流通路DCpath步驟（分壓式偏置共射極電路）：Steps(voltagedividerbiascommonemittercircuit):算集電極-發(fā)射極電壓（Uce

=Vcc-Ic(Rc+Re)）Calculatethecollector-emittervoltage(Uce=Vcc-Ic(Rc+Re)）算基極電流

（β為電流放大倍數(shù)）Calculatethebasecurrent(βisthecurrentgainfactor)

關(guān)鍵：步驟嚴(yán)謹(jǐn)，避免計(jì)算錯(cuò)誤導(dǎo)致Q點(diǎn)偏差Key:FollowrigorousstepstoavoidQ-pointdeviationcausedbycalculationerrors圖解法：Graphicalmethod基于三極管的輸入特性曲線和輸出特性曲線，結(jié)合電路的直流回路方程，通過曲線交點(diǎn)確定靜態(tài)時(shí)的基極電流（Ib）、集電極電流（Ic）和集電極

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發(fā)射極電壓（Uce），這三個(gè)參數(shù)共同構(gòu)成靜態(tài)工作點(diǎn)Q（Ibq、Icq、Uceq）。BasedontheinputandoutputcharacteristiccurvesofthetransistorandtheDCcircuitequationofthecircuit,thebasecurrent(Ib),collectorcurrent(Ic)andcollector-emittervoltage(Uce)atstaticstatearedeterminedbytheintersectionofthecurves.ThesethreeparameterstogetherconstitutethequiescentoperatingpointQ(Ibq,Icq,Uceq).確定靜態(tài)工作點(diǎn)的方法Methodfordeterminingthequiescentoperatingpoint輸入回路Inputcircuit輸出回路Outputcircuit圖解法：Graphicalmethod基于三極管的輸入特性曲線和輸出特性曲線，結(jié)合電路的直流回路方程，通過曲線交點(diǎn)確定靜態(tài)時(shí)的基極電流（Ib）、集電極電流（Ic）和集電極

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發(fā)射極電壓（Uce），這三個(gè)參數(shù)共同構(gòu)成靜態(tài)工作點(diǎn)Q（Ibq、Icq、Uceq）。BasedontheinputandoutputcharacteristiccurvesofthetransistorandtheDCcircuitequationofthecircuit,thebasecurrent(Ib),collectorcurrent(Ic)andcollector-emittervoltage(Uce)atstaticstatearedeterminedbytheintersectionofthecurves.ThesethreeparameterstogetherconstitutethequiescentoperatingpointQ(Ibq,Icq,Uceq).確定靜態(tài)工作點(diǎn)的方法Methodfordeterminingthequiescentoperatingpoint輸入回路Inputcircuit輸出回路Outputcircuit圖解法：Graphicalmethod確定靜態(tài)工作點(diǎn)的方法Methodfordeterminingthequiescentoperatingpoint輸入回路Inputcircuit輸出回路Outputcircuit步驟Steps畫直流負(fù)載線（公式：Uce=Vcc-IcRc）DrawtheDCloadline(formulaUce=Vcc-IcRc)由輸入回路求基極電流（Ib）Calculatethebasecurrent(Ib)fromtheinputcircuit找輸出特性曲線中對應(yīng)Ib的曲線，與直流負(fù)載線交點(diǎn)即為Q點(diǎn)（Ibq、Icq、Uceq）FindthecurvecorrespondingtoIbintheoutputcharacteristiccurve.TheintersectionofthiscurvewiththeDCloadlineistheQpoint(Ibq,Icq,Uceq).優(yōu)勢：直觀反映Q點(diǎn)位置、電路參數(shù)對Q點(diǎn)的影響。Advantages:IntuitivelyreflecttheQpointpositionandtheinfluenceofcircuitparametersontheQpointPart05靜態(tài)工作點(diǎn)對放大電路性能的影響Theinfluenceofquiescentoperatingpointontheperformanceofamplifiercircuit失真類型

DistortionTypeQ點(diǎn)狀態(tài)

Qpointstatus失真原因

Causesofdistortion飽和失真

Saturationdistortion截止失真

Cut-offdistortion過高

High過低

Low輸入信號正半周，lc達(dá)飽和值，Uce過小Inthepositivehalfcycleoftheinputsignal,IcreachesthesaturationvalueandUceistoosmall.靜態(tài)工作點(diǎn)對放大電路性能的影響Theinfluenceofquiescentoperatingpointontheperformanceofamplifiercircuit輸入信號負(fù)半周，Ib

變?yōu)榱?，三極管截止

Inthenegativehalfcycleoftheinputsignal,Ibbecomeszeroandthetransistoriscutoff.失真表現(xiàn)

Distortionperformance輸出信號負(fù)半周被削平Thenegativehalfcycleoftheoutputsignalisclipped輸出信號正半周被削平ThepositivehalfcycleoftheoutputsignalisclippedPart06案例分析Casestudycircuit確定靜態(tài)工作點(diǎn)Determinethequiescentoperatingpoint案例分析Casestudy靜態(tài)工作點(diǎn)對電路性能的影響Theinfluenceofquiescentoperatingpointoncircuit案例分析Casestudy基礎(chǔ)參數(shù)：Basicparameters:電源電壓Vcc=12VPowersupplyvoltageVcc=12V集電極電阻Rc=3kΩCollectorresistorRc=3kΩ基極偏置電阻Rb=300kΩBasebiasresistanceRb=300kΩ三極管電流放大系數(shù)：β=50Transistorcurrentamplificationfactor:β=50用估算法計(jì)算靜態(tài)工作點(diǎn)Determinethequiescentoperatingpointusingtheestimationmethod共射極放大電路

Common-emitteramplifiercircuit集電極電流IcCollectorcurrentIc靜態(tài)工作點(diǎn)的核心參數(shù)Coreparametersofthequiescentoperatingpoint基極電流IbBasecurrentIb集電極-發(fā)射極電壓UceCollector-emittervoltageUce案例分析Casestudy共射極放大電路

Common-emitteramplifiercircuit案例分析Casestudy不同Rb

下的Q點(diǎn)與電路狀態(tài)Q-pointandcircuitstateunderdifferentRbvalues當(dāng)基極偏置電阻Rb=300kΩ時(shí)：WhenthebasebiasresistanceRb=300kΩ:共射極放大電路

Common-emitteramplifiercircuit基極電流

Basecurrent集電極電流

Collectorcurrent集電極-發(fā)射極電壓

Collector-emittervoltage

Uce處于電源電壓的中間區(qū)域Uceislocatedinthemiddlerangeofthepowersupplyvoltage三極管工作在正常放大狀態(tài)Thetransistorisoperatinginnormalamplificationmode.靜態(tài)工作點(diǎn)設(shè)置合理Reasonablequiescentoperatingpointsettings案例分析Casestudy不同Rb

下的Q點(diǎn)與電路狀態(tài)Q-pointandcircuitstateunderdifferentRbvalues情況一：基極偏置電阻減?。≧b=100kΩ）Case1:Whenbasebiasresistancedecreases(Rb=100kΩ)共射極放大電路

Common-emitteramplifiercircuit基極電流

Basecurrent集電極電流

Collectorcurrent集電極-發(fā)射極電壓

Collector-emittervoltage基極電流過大Thebasecurrentistoohigh靜態(tài)工作點(diǎn)上移Thequiescentoperatingpointshiftsupward飽和失真Saturationdistortion

案例分析Casestudy不同Rb

下的Q點(diǎn)與電路狀態(tài)Q-pointandcircuitstateunderdifferentRbvalues情況二：基極偏置電阻增大（Rb=1MΩ）Case2:Whenbasebiasresistanceincreases(Rb=1MΩ)共射極放大電路

Common-emitteramplifiercircuit基極電流

Basecurrent集電極電流

Collectorcurrent集電極-發(fā)射極電壓

Collector-emittervoltage基極電流過小Thebasecurrentistoolow靜態(tài)工作點(diǎn)下移Thequiescentoperatingpointshiftsdownward截止失真Cutoffdistortion

不同Rb下的Q點(diǎn)與電路狀態(tài)Q-pointandcircuitstateunderdifferentRbvaluesQ點(diǎn)合理QpointisreasonableUce在電源電壓中間區(qū)域，三極管正常放大。WhenUceisinthemiddlerangeofthepowersupplyvoltage,thetransistoramplifiesnormally.Q點(diǎn)過高Qpointistoohigh三極管飽和，產(chǎn)生飽和失真。Transistorsaturationcausessaturationdistortion.Q點(diǎn)過低Qpointistoolow三極管接近截止，產(chǎn)生截止失真。Whenatransistorapproachescutoff,cutoffdistortionoccurs.嚴(yán)謹(jǐn)計(jì)算Rigorouscalculating精確調(diào)試Precisedebugging教學(xué)重點(diǎn)梳理

Keypointsofteaching理解靜態(tài)分析的目的（確定Q點(diǎn)）。Understandthepurposeofstaticanalysis(todeterminetheQpoint).掌握估算法、圖解法確定Q點(diǎn)。MastertheestimationmethodandgraphicalmethodtodeterminetheQpoint.