《电子技术（双语）》课件-小电流定乾坤：解析放大电路的静态特性

小元件大作用：探秘半导体二极管Smallcomponentsplayabigimportantrole:exploringsemiconductordiodesTeacher:JiaLisi授课教师：贾丽斯前提：Premise:共射极放大电路可放大微弱信号

Common-emitteramplifiercircuitcanamplifyweaksignals放大电路要稳定工作有哪些关键因素在起作用？Whatarethekeyfactorsthatplayaroleinthestableoperationoftheamplifiercircuit?静态分析是电路稳定工作的“地基”Staticanalysisisthe"foundation"forstablecircuitoperation解析放大电路的静态特性AnalyzethestaticcharacteristicsoftheamplifiercircuitPart01教学目标Teachingobjective掌握Mastery教学目标Teachingobjective估算法、图解法确定静态工作点。Determinethequiescentoperatingpointbyestimationandgraphicalmethods理解Understanding静态工作点与失真的关系。Therelationshipbetweenquiescentoperatingpointanddistortion应用Application准确计算共射极放大电路静态工作点、分析失真。Accuratelycalculatethequiescentoperatingpointofthecommonemitteramplifiercircuitandanalyzethedistortion.素养Literacy培养严谨计算与精确调试能力CultivaterigorouscalculationandprecisedebuggingcapabilitiesPart02案例导入Caseintroduction微弱电台信号Weakradiosignal案例导入Caseintroduction放大电路Amplifiercircuit正常播放Normalplayback微弱电台信号Weakradiosignal案例导入Caseintroduction放大电路Amplifiercircuit静态工作点不当Improperquiescentoperatingpoint声音嘶哑、断续、不清hoarse,intermittent,orinaudiblesound案例导入Caseintroduction声音转化为电信号Convertsoundintoelectricalsignals案例导入Caseintroduction声音转化为电信号Convertsoundintoelectricalsignals静态工作点不当Improperquiescentoperatingpoint播放声音异常Abnormalplaybacksound指放大电路没有输入信号时的工作状态。Staticstatereferstotheoperatingstateofanamplifiercircuitwhennoinputsignalispresent.

此时，电路中只有直流电源作用Duringthisstate,onlytheDCpowersupplyisactinginthecircuit,三极管各电极的电流和电压都是直流值。thecurrentandvoltageacrosseachtransistor'selectrodesareDCvalues.静态StaticstatePart03静态分析的目的Purposeofstaticanalysis确定三极管静态工作点（Q点），参数：基极电流（Ib）、集电极电流（Ic）、集电极-发射极电压（Uce）Todeterminethetransistor'squiescentoperatingpoint(Qpoint),parameters:basecurrent(Ib),collectorcurrent(Ic),collector-emittervoltage(Uce)目的

Purpose静态分析的目的Purposeofstaticanalysis保证三极管始终工作在放大区，避免信号失真，支撑电路正常放大。Ensurethatthetransistoralwaysworksintheamplificationarea,avoidsignaldistortion,andsupportnormalamplificationofthecircuit.作用

FunctionPart04确定静态工作点的方法

Methodfordeterminingthequiescentoperatingpoint如何确定静态工作点Howtodeterminethequiescentoperatingpoint

估算法Estimationmethod图解法Graphicalmethod确定静态工作点的方法Methodfordeterminingthequiescentoperatingpoint估算法：Estimationmethod通过电路的直流通道，利用欧姆定律和三极管的电流关系来计算静态工作点。UseOhm'slawandthetransistorcurrentrelationshiptocalculatethequiescentoperatingpointthroughthecircuit'sDCpath.确定静态工作点的方法Methodfordeterminingthequiescentoperatingpoint断开Opencircuit断开Opencircuit

对直流信号，耦合电容C可看作开路

ForDCsignals,thecouplingcapacitorCcanberegardedasanopencircuit.

直流通路DCpath估算法：Estimationmethod通过电路的直流通道，利用欧姆定律和三极管的电流关系来计算静态工作点。UseOhm'slawandthetransistorcurrentrelationshiptocalculatethequiescentoperatingpointthroughthecircuit'sDCpath.确定静态工作点的方法Methodfordeterminingthequiescentoperatingpoint断开Opencircuit断开Opencircuit

对直流信号，耦合电容C可看作开路

ForDCsignals,thecouplingcapacitorCcanberegardedasanopencircuit.

直流通路DCpath估算法：Estimationmethod确定静态工作点的方法Methodfordeterminingthequiescentoperatingpoint断开Opencircuit断开Opencircuit

对直流信号，耦合电容C可看作开路

ForDCsignals,thecouplingcapacitorCcanberegardedasanopencircuit.

直流通路DCpath步骤（分压式偏置共射极电路）：Steps(voltagedividerbiascommonemittercircuit):算基极电位（Ub）Calculatethebasepotential(Ub)算发射极电位（Ue=Ub-Ube，硅管Ube≈0.7V，锗管≈0.3V）Calculatetheemitterpotential(Ue=Ub-Ube,Ube≈0.7Vforsilicondiodes,0.3Vforgermaniumdiodes)算发射极电流Calculatetheemittercurrent

估算法：Estimationmethod确定静态工作点的方法Methodfordeterminingthequiescentoperatingpoint断开Opencircuit断开Opencircuit

对直流信号，耦合电容C可看作开路

ForDCsignals,thecouplingcapacitorCcanberegardedasanopencircuit.

直流通路DCpath步骤（分压式偏置共射极电路）：Steps(voltagedividerbiascommonemittercircuit):算集电极-发射极电压（Uce

=Vcc-Ic(Rc+Re)）Calculatethecollector-emittervoltage(Uce=Vcc-Ic(Rc+Re)）算基极电流

（β为电流放大倍数）Calculatethebasecurrent(βisthecurrentgainfactor)

关键：步骤严谨，避免计算错误导致Q点偏差Key:FollowrigorousstepstoavoidQ-pointdeviationcausedbycalculationerrors图解法：Graphicalmethod基于三极管的输入特性曲线和输出特性曲线，结合电路的直流回路方程，通过曲线交点确定静态时的基极电流（Ib）、集电极电流（Ic）和集电极

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发射极电压（Uce），这三个参数共同构成静态工作点Q（Ibq、Icq、Uceq）。BasedontheinputandoutputcharacteristiccurvesofthetransistorandtheDCcircuitequationofthecircuit,thebasecurrent(Ib),collectorcurrent(Ic)andcollector-emittervoltage(Uce)atstaticstatearedeterminedbytheintersectionofthecurves.ThesethreeparameterstogetherconstitutethequiescentoperatingpointQ(Ibq,Icq,Uceq).确定静态工作点的方法Methodfordeterminingthequiescentoperatingpoint输入回路Inputcircuit输出回路Outputcircuit图解法：Graphicalmethod基于三极管的输入特性曲线和输出特性曲线，结合电路的直流回路方程，通过曲线交点确定静态时的基极电流（Ib）、集电极电流（Ic）和集电极

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发射极电压（Uce），这三个参数共同构成静态工作点Q（Ibq、Icq、Uceq）。BasedontheinputandoutputcharacteristiccurvesofthetransistorandtheDCcircuitequationofthecircuit,thebasecurrent(Ib),collectorcurrent(Ic)andcollector-emittervoltage(Uce)atstaticstatearedeterminedbytheintersectionofthecurves.ThesethreeparameterstogetherconstitutethequiescentoperatingpointQ(Ibq,Icq,Uceq).确定静态工作点的方法Methodfordeterminingthequiescentoperatingpoint输入回路Inputcircuit输出回路Outputcircuit图解法：Graphicalmethod确定静态工作点的方法Methodfordeterminingthequiescentoperatingpoint输入回路Inputcircuit输出回路Outputcircuit步骤Steps画直流负载线（公式：Uce=Vcc-IcRc）DrawtheDCloadline(formulaUce=Vcc-IcRc)由输入回路求基极电流（Ib）Calculatethebasecurrent(Ib)fromtheinputcircuit找输出特性曲线中对应Ib的曲线，与直流负载线交点即为Q点（Ibq、Icq、Uceq）FindthecurvecorrespondingtoIbintheoutputcharacteristiccurve.TheintersectionofthiscurvewiththeDCloadlineistheQpoint(Ibq,Icq,Uceq).优势：直观反映Q点位置、电路参数对Q点的影响。Advantages:IntuitivelyreflecttheQpointpositionandtheinfluenceofcircuitparametersontheQpointPart05静态工作点对放大电路性能的影响Theinfluenceofquiescentoperatingpointontheperformanceofamplifiercircuit失真类型

DistortionTypeQ点状态

Qpointstatus失真原因

Causesofdistortion饱和失真

Saturationdistortion截止失真

Cut-offdistortion过高

High过低

Low输入信号正半周，lc达饱和值，Uce过小Inthepositivehalfcycleoftheinputsignal,IcreachesthesaturationvalueandUceistoosmall.静态工作点对放大电路性能的影响Theinfluenceofquiescentoperatingpointontheperformanceofamplifiercircuit输入信号负半周，Ib

变为零，三极管截止

Inthenegativehalfcycleoftheinputsignal,Ibbecomeszeroandthetransistoriscutoff.失真表现

Distortionperformance输出信号负半周被削平Thenegativehalfcycleoftheoutputsignalisclipped输出信号正半周被削平ThepositivehalfcycleoftheoutputsignalisclippedPart06案例分析Casestudycircuit确定静态工作点Determinethequiescentoperatingpoint案例分析Casestudy静态工作点对电路性能的影响Theinfluenceofquiescentoperatingpointoncircuit案例分析Casestudy基础参数：Basicparameters:电源电压Vcc=12VPowersupplyvoltageVcc=12V集电极电阻Rc=3kΩCollectorresistorRc=3kΩ基极偏置电阻Rb=300kΩBasebiasresistanceRb=300kΩ三极管电流放大系数：β=50Transistorcurrentamplificationfactor:β=50用估算法计算静态工作点Determinethequiescentoperatingpointusingtheestimationmethod共射极放大电路

Common-emitteramplifiercircuit集电极电流IcCollectorcurrentIc静态工作点的核心参数Coreparametersofthequiescentoperatingpoint基极电流IbBasecurrentIb集电极-发射极电压UceCollector-emittervoltageUce案例分析Casestudy共射极放大电路

Common-emitteramplifiercircuit案例分析Casestudy不同Rb

下的Q点与电路状态Q-pointandcircuitstateunderdifferentRbvalues当基极偏置电阻Rb=300kΩ时：WhenthebasebiasresistanceRb=300kΩ:共射极放大电路

Common-emitteramplifiercircuit基极电流

Basecurrent集电极电流

Collectorcurrent集电极-发射极电压

Collector-emittervoltage

Uce处于电源电压的中间区域Uceislocatedinthemiddlerangeofthepowersupplyvoltage三极管工作在正常放大状态Thetransistorisoperatinginnormalamplificationmode.静态工作点设置合理Reasonablequiescentoperatingpointsettings案例分析Casestudy不同Rb

下的Q点与电路状态Q-pointandcircuitstateunderdifferentRbvalues情况一：基极偏置电阻减小（Rb=100kΩ）Case1:Whenbasebiasresistancedecreases(Rb=100kΩ)共射极放大电路

Common-emitteramplifiercircuit基极电流

Basecurrent集电极电流

Collectorcurrent集电极-发射极电压

Collector-emittervoltage基极电流过大Thebasecurrentistoohigh静态工作点上移Thequiescentoperatingpointshiftsupward饱和失真Saturationdistortion

案例分析Casestudy不同Rb

下的Q点与电路状态Q-pointandcircuitstateunderdifferentRbvalues情况二：基极偏置电阻增大（Rb=1MΩ）Case2:Whenbasebiasresistanceincreases(Rb=1MΩ)共射极放大电路

Common-emitteramplifiercircuit基极电流

Basecurrent集电极电流

Collectorcurrent集电极-发射极电压

Collector-emittervoltage基极电流过小Thebasecurrentistoolow静态工作点下移Thequiescentoperatingpointshiftsdownward截止失真Cutoffdistortion

不同Rb下的Q点与电路状态Q-pointandcircuitstateunderdifferentRbvaluesQ点合理QpointisreasonableUce在电源电压中间区域，三极管正常放大。WhenUceisinthemiddlerangeofthepowersupplyvoltage,thetransistoramplifiesnormally.Q点过高Qpointistoohigh三极管饱和，产生饱和失真。Transistorsaturationcausessaturationdistortion.Q点过低Qpointistoolow三极管接近截止，产生截止失真。Whenatransistorapproachescutoff,cutoffdistortionoccurs.严谨计算Rigorouscalculating精确调试Precisedebugging教学重点梳理

Keypointsofteaching理解静态分析的目的（确定Q点）。Understandthepurposeofstaticanalysis(todeterminetheQpoint).掌握估算法、图解法确定Q点。MastertheestimationmethodandgraphicalmethodtodeterminetheQpoint.