華中科技電子與信息工程系大二上學(xué)期學(xué)習(xí)模電

HuazhongUniversityofScienceandTechnologyTheDepartmentofElectronicsandInformationEngineeringFirstTerm09/10ElectronicCircuitAnalysisandDesignDr.

TianpingDengEmail:PART1

SEMICONDUCTORDEVICESANDBASICAPPLICATIONS

Chapter1

SemiconductorMaterialsandDiodes

Chapter2

DiodeCircuits

Chapter3

TheField-EffectTransistor

Chapter4

BasicFETAmplifiers

Chapter5

TheBipolarJunctionTransistor

Chapter6

BasicBJTAmplifiers

Chapter7

FrequencyResponse

Chapter8

OutputStagesandPowerAmplifiersPART2

ANALOGELECTRONICS

Chapter9

IdealOperationalAmplifiersandOp-AmpCircuits

Chapter10

IntegratedCircuitBiasingandActiveLoads

Chapter11

DifferentialandMultistageAmplifiers

Chapter12

FeedbackandStability

Chapter13

OperationalAmplifierCircuits

Chapter14

NonidealEffectsinOperationalAmplifierCircuits

Chapter15

ApplicationsandDesignofIntegratedCircuitsContentsChapter5

TheBipolarJunctionTransistorCh5.TheBipolarJunctionTransistor5.1.1TransistorStructure5.1.2NPNTransistor:Forward-ActiveModeOperation5.1BasicBipolarJunctionTransistor5.1.3Current-VoltageCharacteristic5.1.4BJTMainParameters雙極性參數(shù)Ch5.TheBipolarJunctionTransistor5.0PreviewDiodesareusefulinwaveshapingandswitchingcircuits,butnotcapableofamplifyingcurrentsorvoltages.u2uo

t

2340Ch5.TheBipolarJunctionTransistorTransistoriscapableofcurrentandvoltageamplification,itisathree-terminaldevice_Revolution.Ch5.TheBipolarJunctionTransistor5.0PreviewWediscusstheDCandACanalysisanddesignofbipolarcircuits.Transistorhastwoclasses,oneisthebipolartransistor,whichhastwomajortypes,otheristhefiled-effecttransistor(FET).Webegintointroducethephysicalstructureandoperation

ofthebipolartransistor.TransistorBJTFET5.1BasicBipolarJunctionTransistor(BJT)5.1.1TransistorStructureTherearetwotypesofbipolartransistor:NPNandPNP.B-Ejunction

B-CjunctionBaseterminal

EmitterterminalCollectorterminal

EmitterCollectorBaseSymbolThreeregions:ThreeterminalsTwopnjunctions:Theemitterisdistinguishedbythearrowhead.5.1.1TransistorStructureFeatureoftransistorstructureCrosssectionofNPNbipolarTransistor(3)Basemustbeverynarrow.(1)Impuritydopingconcentrationinemitterregionismuchlargerthanothertworegions.(2)Areaofcollectorregionisbiggerthanthatofemitter.濃度5.1.2NPNTransistor:Forward-ActiveModeOperationAmplificationconditionItiscalledtheforward-activeoperatingmode,oractiveregion.1.Transferprocessofcarriersinnpn(1)Emitterregionemitelectronsintobase.(2)Collectorregioncollectelectronsinjectedbasefromemitter.(3)B-Evoltagecontrolscollectorcurrent.Iftransistorisusedasanamplifyingdevice.B-Ejunctionisforwardbiased.B-Cjunctionisreversebiased.NPNbipolartransistorbiasedintheforward-activemodeB-Ejunctionisforwardbiased.B-Cjunctionisreversebiased.5.1.2NPNTransistor:Forward-ActiveModeOperation1.Transferprocessofcarriers5.1.2NPNTransistor:Forward-ActiveModeOperationTherearetwotypesofcarriers,electronsandholescontributingtothecurrent,sothetransistoriscalledbipolarjunctiontransistor(BJT).EmitterCurrent

VT

__thermalvoltage

IES

__emitterleakagecurrent

2.CurrentrelationshipsIE=IB+IC,IC=InC+ICBO,IB=IB’-ICBO

TransferprocessofcarriersWeknowfromtransferprocessofcarriersgenerally

IC>>ICBOmon-basecurrentgain,onlydependongeometriesandconcentration,norelationwithvoltages.Generally=0.90.992.CurrentrelationshipssinceIE=IB+IC

,IC=InC+ICBO,

iscommon-emittercurrentgain,also,onlydependongeometriesandimpurityconcentration,independentofB-CandB-Evoltages.Generally

50<

<

300.assumeICEO=(1+

)ICBO（leakagecurrent）IE=IB+IC2.Currentrelationships3.ThreeTypesofCircuitConfigurationsCommon-emitter，emitterisacommonterminal，brieflyCE；Common-base，baseisacommonterminal，brieflyCB；Common-collector，collectorisacommonterminal，brieflyCC；BJTCircuitConfigurationsWhichConfigurationcanamplifycurrent?5.1.2NPNTransistor:Forward-ActiveModeOperationInordertousethetransistorasanamplifyingdevice,thetwoconditionsmustbesatisfied:Internalcondition:Impurityconcentrationinemitterregionismuchlargerthanthatinthebaseregion.Baseregionmustbeverynarrow.Externalcondition:B-Ejunctionisforwardbiased.B-Cjunctionisreversebiased.

Forthepnptransistor,itisthecomplementarydevicetothenpntransistor,soallthevoltagespolaritiesandcurrentsdirectionsaretheoppositetothenpntransistor.5.1.3Current-VoltageCharacteristics1.InputcharacteristicofCE

iB=f(vBE)

vCE=const（TakingCEcircuitase.g.)(2)WhenvCE≥1V，vCB=vCE-vBE>0，B-Cisreversebiased，someelectronsbegintosweepintocollector,binationdecreasesinbase,soIBreducesundersamevBE，(1)whenvCE=0V,itissameasforwardexponentialrelationofadiode。Common-emittercircuitcurveshiftstoright。5.1.3Current-VoltageCharacteristics2.TheoutputCharacteristicofCE

iC=f(vCE)

iB=const5.1.3Current-VoltageCharacteristics2.OutputcharacteristicofCE(Transistorcharacteristic)iC=f(vCE)

iB=constSaturation：iCiscontrolledbyvCE,iCincreasesrapidlyasvCEincreases,andvCE＜0.7V(Silicon)。B-Eisforwardbiased,B-Cisforwardbiased,too,orvoltageofreversebiasedisverysmall.Fourregionsforcharacteristic5.1.3Current-VoltageCharacteristics2.OutputcharacteristicofCE(Transistorcharacteristic)iC=f(vCE)

iB=constFourregionsforcharacteristicCut-off：iCisnearlyzero，Cut-offregionisunderiB=0。vBE<VB

(turninvoltage),B-Cisreversebiased。5.1.3Current-VoltageCharacteristics2.OutputcharacteristicofCE(Transistorcharacteristic)iC=f(vCE)

iB=constFourregionsforcharacteristicBreakdown:Reverse-biasvoltageofB-Cincreasestoomuch,B-Cjunctionbegintobreakdown.5.1.3Current-VoltageCharacteristics2.OutputcharacteristicofCE(Transistorcharacteristic)iC=f(vCE)

iB=constFourregionsforcharacteristicForward-activemode：

iCandiBarerelatedbyiC=iB.Curvesareparallelandequidistance.B-Eisforwardbiased,B-Cisreversebiased.ModesofOperation5.1.3Current-VoltageCharacteristics2.TheoutputCharacteristicofCECurrent-voltagecharacteristicsforthecommon-emittercircuit,showingtheEarlyvoltage5.1.3Current-VoltageCharacteristics2.TheoutputCharacteristicofCE5.1.3Current-VoltageCharacteristics3.TheoutputCharacteristicofCBWhytheVCBcanbenegative?5.1.4BJTMainParameters1.CurrentGain

(1)Common-emitterdccurrentgain

F

F=（IC－ICEO）/IB≈IC/IB

vCE=const5.1.4BJTMainParameters1.CurrentGain

(2)Common-emitteraccurrentgain

=

IC/

IB

vCE=const5.1.4BJTMainParameters1.CurrentGain

(3)Common-basedccurrentgainαF

αF

=（IC－ICBO）/IE≈IC/IE

WhenICBOandICEOareverysmall,

F≈

,

F

≈

.(4)Common-baseaccurrentgainαα=

IC/

IE

VCB=const5.1.4BJTMainParameters2.Reverse-biasLeakageCurrents

(2)Collector-emitterleakagecurrentICEOICEO=（1+

F

）ICBO

(1)Collector-baseleakagecurrentICBOInmostinstancesinthistext,leakagewillbecompletelynegligible. ICBOisthecollectorleakagecurrentincommon-baseconfiguration,whentheemitterisanopencircuit.ICEO5.1.4BJTMainParameters3.BreakdownVoltageBVCBO——Collector-basejunctionbreakdownvoltageinopen-emitterconfiguration。BVCEO——Breakdownvoltagebetweencollectorandemitterinopen-baseconfiguration.BVEBO——Base-emitterjunctionbreakdownvoltageinopen-collectorconfiguration。V(BR)CBO＞V(BR)CEO＞V(BR)EBOThesewillbealimitingfactorsinthesizeofthedcbiasvoltageswhichcanbeused.ReviewQuestions(1)DuetoaBJThastwopnjunction,canweconjointwoback-to-backdiodestobeasaBJT?Why?？(2)CanweexchangetheemitterandcollectorterminalsofaBJT,whenweuseitasaamplifyingdevice?(3)WhywecallaBJTasacurrent-controlleddevice?ReviewQuestions4.Thevoltagevaluesforthreeterminalsaregiven,determinetheregionwhichBJToperatesin.(1)VC=6V,VB=0.7V,VE=0V,(2)VC=6V,VB=6V,VE=5.4V,(3)VC=6V,VB=4V,VE=3.6V,(4)VC=3.6V,VB=4V,VE=3.4V,？(1)VC=6V,VB=0.7V,VE=0VVBE=0.7V>Vth=0.5VVCE=6VVC>VB>VEForwardactiveregion(2)VC=6V,VB=6V,VE=5.4VVBE=0.6V>Vth=0.5VVCE=0.6VVC=VB>VESaturationRegion(3)VC=6V,VB=4V,VE=3.6VVBE=0.4V<0.5VCutoffregione)VC=3.6V,VB=4V,VE=3.4VVBE=0.6VVCE=0.2VSaturationRegionReviewQuestions5.AssumeI1=–1.2mA,I2=–0.03mA,I3=1.23mA，？(1)Determine①