哈工大高频电路课设概述

.CoursedesignofhighfrequencyelectroniccircuitSchool:SchoolofElectronicandInformationEngineering.Class:Class1105102Name:Su*inNo.:1111900211Date:November9,2013.Idesignrequirements1.1designcontentDesignoftransmittingsystemofmediumwaveradiostationThepurposeofthedesignistomasterthedesign,installationanddebuggingofthemostbasiclow-powerAMtransmittingsystem.Technicalspecifications:thecarrierfrequencyis535-1605KHz,thecarrierfrequencystabilityisnotlessthan10-3,theoutputloadis51Ω,thetotaloutputpoweris50mW,andtheamplitudemodulationinde*is30%-80%.Themodulationfrequencyis500Hz~10kHz.DesignofmediumwaveradioreceivingsystemThepurposeofthisprojectistomasterthedesignanddebuggingofthemostbasicsuperheterodynereceiver.Task:MaintechnicalindicatorsofAMAMamplitudemodulationreceivingsystemdesign:carrierfrequency535-1605KHz,intermediatefrequency465KHz,outputpower0.25W,loadresistance8ω,sensitivity1mV.1.2designrequirementsRequiredtasks(foreachsystem):Detailedfunctionalblockdiagramofsystemdesignisgivenforeachsystem.Accordingtothetechnicalindicatorsandrequirementsofthetaskandthefunctionalblockdiagramofthesystem,thedetailedcalculationprocessofparametercalculation,schemedemonstrationanddeviceselectionisgiven.Thedetailedcircuitschematicdiagramisgiven,theinputandoutputofthecircuitmodulearemarked,andthedetailedmathematicalmodelandcalculationprocessaregiven.Selectedtask(foreachsystem):thispartofthecompletionhase*trapoints.ThewholecircuitissimulatedbyADSandothercomputersoftware,andtheinputandoutputsimulationwaveformsandanalysisoffunctionnodesandsystemaregiven.Designandsimulationofthetransmittingsystemofthesecondmediumwaveradiostation2.1Systemdesignoflow-powerAMtransmitterThesystemschematicdiagramisshowninFigure2.1:.载波信号正弦振荡器 缓冲电路 高频小信号放大 振幅调制电路 高频功率放大 天线调制信号声电变换 前置放大器 低频放大Figure2-1SystemDesignBlockDiagramofLowPowerAMTransmitter2.2workingprincipleanddescriptionInFigure2-1,thefunctionsofeachcomponentareasfollows:Sinusoidaloscillator:generatesacarriersignalwithafrequencyofMHz.Bufferstage:thesineoscillatorisisolatedfromthemodulationcircuittoreducetheinfluenceofthemodulationstageonthesineoscillator.Lowfrequencyamplificationstage:amplifythemicrophonesignalvoltagetothemodulationvoltagerequiredbythemodulationstage.Amplitudemodulation:modulatingthevoicesignalontothecarrierwavetoproducethemodulatedwave.Andthepoweramplifierantenna:amplifyingthepowerofthesignalsentbythepreviousstage,andtransmittingthemodulatedhigh-frequencycarriercurrentintospaceintheformofelectromagneticwavesthroughtheantenna.Now,combinetheperformanceindicatorsgiveninthetitleforanalysis:Thecarrierfrequencyis535-1605KHz,andthestabilityofthecarrierfrequencyisnotlessthan10-3:thefrequencyofsinewavesignalgeneratedbysinewaveoscillatoris535KHzto1605KHz.Whentheoscillationwaveformisunstable,themagnitudeofthema*imumfluctuationfrequencytofrequencyratioislessthan10-3.为f与频率f之比的数量级小于Output51Ω:Theoutputloadoftheoutputpart,thatis,thehigh-frequencypoweramplifier,is51.。Totaloutputpowerof50mW:thatis,theoutputpowerofhigh-frequencypoweramplifier,whichcanbeanalyzedwiththecalculationformulatoachievethetarget.PUcmIc1m可进行分析，实现指标。Amplitudemodulationinde*30%~80%:LetAbethepeakvalueofamplitudemodulationwaveformandBbethevalleyvalue,thentheformulaforcalculatingamplitudemodulationinde*isasfollows.Intheamplitudemodulationcircuit,thisinde*canbeachievedbychangingtheamplitudeofthemodulatedsignal.mAB100%aAB。在振幅调制电路中可通过更改调制信号振幅实现此指标。Modulationfrequency:500Hz~10kHz:thefrequencyofthemodulationsignalisdeterminedbythe.frequencyoftheinputsignal.2.3Specificdesignandanalysisofeachpart2.3.1sinewaveoscillatorandbuffercircuitSinewaveoscillatorisusedtoproducehigh-frequencyoscillationcarriersignalofabout0.535~1.605MHz.Becausethefrequencystabilityofthewholetransmitterisdeterminedbythemainvibrationlevel,itisrequiredthatthemainvibrationlevelshouldhavehighfrequencystabilityandcertainoscillationpower,anditsoutputwaveformdistortionissmall.Therefore,hereIuseSilleroscillatorcircuit,whichcanmeettherequirements.Inordertoreducetheinfluenceofthebackstageontheoscillationfrequencyofthemainoscillatorcircuit,Iusebufferstage.Thebuffercircuitadoptsemitterfollower,whichischaracterizedbyhighinputimpedanceandlowoutputimpedance,sothecurrentrequiredfromthesignalsourceissmallandtheloadcapacityisstrong.Usingittoconnecttwocircuitscanreducetheimpactofdirectconnectionbetweencircuitsandplayabufferingrole.Whentheoscillatoriscascadedwiththebuffer,theoutputvoltageofthebufferstagewillobviouslydecreaseorthewaveformwillbedistorted.Theinputimpedanceofthebufferinputstagecanbeimprovedbyincreasingtheemitterresistance ofthebufferstage,orbyreducingthe,thatis,thecouplingbetweenthemainoscillationstageandthebufferstage.Atthesametime,theload willalsohaveagreatinfluenceontheoutputwaveformofthebuffer.AsshowninFigure2-2.Fore*ample,thetriodeofSilleroscillatorcircuitworksintheamplificationarea.Figure2-2Clickthe togettheoutputwaveformandvoltageandcurrentvalues.Theresultsareasfollows:.Sensitivityis1mV,frequencyis1.166MHz,frequencycounterdoesnotfloat,itisverystable,andfrequencystabilityisstable.Meetthetechnicalindicators.Parametercalculation:Selecttheappropriatetriodefirst,withtheparametersasshowninthefigure.Inthise*periment,theidealtransistor2sc945isadopted,andtherelatedparametersareappro*imately9013,whichisconvenientandfasttoadjustduringsimulation.(Because9013isnotfoundinthesimulationsoftware,andBaiducomponentsonlyhave9013,sofindasimilaroneinthesimulation).ParametersofDCbiascircuit:assumethatthepowersupplyis12V.Inordertopreventthepowersupplyfrombeingdirectlyconnectedtothecircuit,the100uFelectrolyticcapacitorisconnectedinparallelbecausethesuddenchangewillaffectthesafetyandstabilityofthecircuit.UCC为.Theworkingstateoftheoscillatorisrelatedtotheselectionofthestaticworkingpointandthestrengthofpositiveandnegativefeedback.Thebiascircuitadoptsavoltage-dividingcurrentfeedbackbiascircuit,whichmakesthestaticworkingpointmorestable.Make7.5V=3mA.UCEQ7.5VICQRRR=1.5K。Itcanbecalculatedbyformula(2.1)tobe=1.5k.Ce1e2IUUCCCEQCQRRR（2.1）Ce1e2UI(RR)U（2.2）BQCQe1e2BEQUBQRR•UCCb1b1b2（2.3）Inordertoobtainlargefeedback,theemitterresistanceshouldbeaslargeaspossible,taking=560,=47,=1K.Calculatedby(2.2)=3.76V.RC=560，Re1=47，Re2=1K。由（UBQ=3.76VItcanbeknownfromformula(2.3)that=0.31.Tofacilitatetheadjustment,a22Kseriesresistorwitha100Kadjustableresistorisused.Forstability,someothercapacitorsandinductorsareused,whichwillnotbeRb1describedhere.Rb1Rb2=0.31串联一个的可调电阻。为了稳定度，用一些其他的电容电感，在这里不再赘述。OscillatingparameterofSillercircuit:ifthefrequencyis1.166MHzandL=56,thetotalcapacitanceis300.Let=470,=1000,=270,=150(fortheconvenienceofadjustingparameters,divideitinto100fi*edcapacitorsconnectedinparallelwith100adjustablecapacitors).H，则总电容pF。不妨设C1=470pF，CC=270pF，C2=1000pF，34=150pF（为方便调节参数，将之拆为pF固定电容与pF可调电容并联）。CCCC4123121323（2.4）f102LC（2.5）Parametersofbuffercircuit:Uceq=8.7V,=3.1mA.Itcanbetakenasa1Krheostat,andReisa560IRx2为变阻器，电阻。resistor.CQ=3.1mACombine(2.2)with(2.3)sothatRb22=11KandRB21=4.7k.，。2.3.2High-frequencysmallsignalamplifiercircuitThetriodeisanidealtransistor,withtheamplificationfactor=100.=100.U I9V=1.2mA.SoR5=2.5k

CEQ

9V

CQUR

I

UThen=3.7V..Accordingto(2.3),let=5K,andR2isa100Kadjustableresistor.

BQ

5

CQ

BEQ=3.7VR1=5K，可调电阻。Fromthecenterfrequency=1.166MHz,combinedwithformula(2.5),itcanbeknownthatL=80,=300,andthetwocapacitorsareconnectedinparalleltofacilitatetheadjustment.f0=1.166MHzH，C=300pF，两电容并联便于调节。Magnification:Yfe=0.046S(2.6)(2.7)ggoegLg0Whereistheoutputconductanceoftriode,whichiszerounderidealtriodecondition.Istheloadconductance,equalto0.067mS,andistheinductanceconductance,equalto0.05mS..Therefore=0.117ms.goe为三极管11输出电导，理想三极管条件下为零。gL为负载电导，等于15K，即g0为电感电导，等于20K，g=0.117mSAyfeu0g（2.8）AFrom(2.12),theamplificationgain=51.89dB.u0=51.89dBThewholecircuitisshowninthefigure..Itcanbeseenthatthiscircuitcanachievethema*imumamplificationaround1.166MHz,andthegainis53.454dB,whichisclosetothecalculatedresult.2.3.3AmplitudemodulationcircuitDoublebalancedfourquadrantmultiplierisadopted.Thesignalobtainedaftertheabovemultiplieris.Istheamplitudeofthecarriersignal,thefrequencyofthecarriersignal,andthefrequencyofthemodulatedsignal,whichisbetween500Hzand1KHz.u(t)U(1cmost)cost。Ucm为载波信号幅度，cmacc为载波信号频率，为调制信号频率，有题设可知，在.m ABaAB(2.9)WhereAisthepeakvalueofAMsignal,andBisthevalleyvalueofAMsignal.InthiscircuitMa>30%2.4Jointsimulation.DesignofThree-mediumWaveRadioReceivingSystem3.1superheterodyneamplitudemodulationreceivingsystemThesystemblockdiagramisasfollows天线输入回路混频器中频放大器检波器低频电压放低频功率放大器大器正弦振荡器Now,combinetheperformanceindicatorsgiveninthetitleforanalysis:Carrierfrequency535-1605KHz:Thefrequencyofthewaveformgeneratedbythesinewaveoscillatoris.535-1605KHz,soyoucandesignthecircuitthroughrelevantknowledge.f为Intermediatefrequency465KHz:theoutputsignalfrequencyofthemi*eris465KHz,andthemi*eractuallysubtractsthefrequenciesofthetwoinputsignals,sothisperformanceinde*showsthatthesignalwiththefrequencyof465KHzisobtainedafterthesubtractionofthetwofrequencies.Outputpower0.25W:theoutputpoweroftheoutputmodule,thatis,thelow-frequencypoweramplifier,is0.25W..Load8ω:theoutputresistanceoftheinputmodule,whichcanbematchedbycalculationbasedontherelevantknowledgeofthecircuit.Sensitivity1mV:Sensitivityisusedtocharacterizethesensitivityofnetworkcharacteristicstothechangeofcomponentparameters.ThechangerateofnetworkfunctionHornetworkresponseR(collectivelyrepresentedbyT)tosomecomponent-relatedparameters(Pcanbethecomponentparametersorthetemperature,humidity,pressure,etc.thataffectthecomponentparameters)iscalledtheabsolutesensitivityofnetworkfunctiontothisparameter,whichisrecordedas:p(THThereissensitivitytestinthesimulationsoftware,whichcanbedirectlyusedtoanalyzethecircuit.3.2.1LocaloscillatorSimilarly,thelocaloscillatorcanusetheSillercircuitofthetransmittingsystemtogenerateoscillation.3.2.2Designofmi*ercircuitAccordingtotherequirementthatthecenterfrequencyis465Khz,thefrequencyofthelocaloscillatorisfL=fs+465Khz=1.631MHZ.Itwillnotbedebuggedhere,andthesinewavewiththefrequencyof1.631MHZwillbedirectlyusedinthesubsequentcircuits.Therelevantformulaofmi*eris:coscos[cos()cos()]2（3.1）Itcanbeunderstoodthatthesumanddifferencefrequenciesaregeneratedfortheamplitudemodulationsignalfrequencyquantityandthelocaloscillatorfrequencyquantity.为调幅信号频率量，为本振频率量，产生和差频。Themi*ingprinciplediagramisasfollows:.Theoscilloscopewaveformisasfollows.Theleftpictureshowstheamplitudemodulationsignalwaveformwithafrequencyof465KHz.Inthefigureontheright,forthewaveformafterthetimea*isise*tended,itcanbeseenthatthewaveformhasnodistortionandisconsistentwiththewaveformrequiredbytheprevioustheoreticalanalysis..3.3Detectioncircuit3.3.1DesignofDetectionCircuitSmallsignaldetectionmeansthattheamplitudeofhigh-frequencyinputsignalislessthan0.2v,thefrequencyisconvertedbythebentpartofdiodevolt-amperecharacteristic,andthenthedetectionisrealizedbylow-passfilter.Animportantproblemofdiodeenvelopedetectionistopreventdistortion.Therearethreemainsourcesofdistortion:(1)distortioncausedbynonlinearityofdiodevolt-amperecharacteristics;(2)Inertialdistortioncausedbye*cessivedetectionloadtimeconstant;(3)Distortionofflat-bottomcuttingcausedbydifferentACandDCvaluesofdetectionload.Forthedistortioncausedbythenonlinearityofthediode'svolt-amperecharacteristics,aslightforwardbiasvoltagecanbeappliedtothediodetomakeitsstaticworkingpointneartheconductionpoint,thusreducingthedistortioncausedbythediode'sconductionvoltagenotbeingzero.Anyconditionthatinertiadistortiondoesnotoccurinstantlyis:√1-mRC≤ᵅᵄᵯᵄ2（3.2）And,modulatethefrequency.som0.33，2f23.1410006.28103rads。所a0以RC10.3320.456103R5K0.336.28103，(3.3)Mayaswelltake,.1C25nF。1mRACTheconditionthatnoundercuttingdistortionoccursatanymomentis:,whereaRDC，其中R R //R(3.4)AC 1 2R R（3.5）DC 1=5again,sotake=10.DCblockingcapacitor=10.R1=5K，因此取R2=10K。取隔直电容C2=10F。Theoutputwaveformisasfollows,whiteisthemodulationsignal,andredistheenvelopedetection.output. withgoodfidelitycanbeseen.3.4Low-frequencyvoltageamplifyingcircuit3.4.1DesignofLowFrequencyVoltageAmplifierCircuitConnectanoscilloscopeattheoutputendtoobservewhetherthewaveformisdistorted,andobservetheequivalentamplitude-frequencycharacteristicswithPorterinstrument,andmeasurethefrequency,voltageandcurrent.Thecircuitdiagramisasfollows:.IV.E*perie