5990-3356EN利用现有的增益测量流程和 ADS 电磁电路协同仿真功能进行

AgilentTechnologiesPracticalRFAmplifierDesignUsingtheAvailableGainProcedureandtheAdvancedDesignSystemEM/CircuitCo-SimulationCapabilityWhitePaperbyKenPayneAbstractThisarticlefeaturesamethodofdesigningalownoiseRFamplifierforan802.11breceiverapplicationandcontainsanAvagoATF54143PHEMTtransistor.ADSdesigntoolsareusedsuchthatthetechniquespresentedremovemuchoftheguessworkfromthedesignpro-cess.DesignspeedandcostalongwithRFperformanceareofutmostimportanceformostRFdesigns,thus,oneofthemainobjectivesistoyieldadesignthatworkswiththefirstPCBpass.Ifsuccessful,multiplePCBlayoutsareavoided,whichsavesdesigncostandtime.ThisdesignprocedureisconsideredsuccessfulevenifsomeofthelumpedcomponentvalueshavetobeadjustedslightlytogetthedesiredRFperformance–aslongasthelayoutdoesnothavetobemodifiedtohaveaworkingcircuit.Itisalsoconsideredsuccess-fulevenifthemodelpredictiondoesn’texactlyagreewithmeasuredresults,buttheresultingcircuitstillmeetsthedesigncriteriaandspecifications.Thefeaturedamplifiercoversafrequencyrangeof2.4GHzto2.48GHz.Thedesignisillustratedfromstarttofinish,withconstructionofaprintedcircuitboardandmeasurementresults.IntroductionAnamplifiercircuitconsistsmainlyofagaindeviceordevices,andinputandoutputmatchingorcouplingnetworks.Theamplifiershouldmakeweaksignalslargerwithoutaddingtoomuchnoiseordistortion.Ideally,theamplifierwouldaddnonoiseandwouldnotdistortthesignalinanyway.Electronicdevicesarenotidealhowever,andthusdegradethesignaltosomedegree.Theamplifierdesignobjectiveistominimizethenoiseaddedandthedistortioncreatedwhileincreasingtheamplitudeofthesignal.Designtrade-offsallowonetoobtainthebestpossibleperformancefromaparticularactivedevice.Figure12Abstract.......................................................................................................................................CoverIntroduction.................................................................................................................................CoverBackground.........................................................................................................................................3TransducerGain.................................................................................................................................3StabilityAnalysis................................................................................................................................4AvailableGainDesignProcedure...................................................................................................5NoiseFigureDesignProcedure.......................................................................................................6802.11bAmplifierDesignRequirements.......................................................................................7TransistorS-ParametersandNonlinearModel............................................................................8S-ParameterDataValidation.........................................................................................................11ATF54143Stability...........................................................................................................................14AmplifierEM/CircuitCo-SimulationandPCBFabrication.......................................................29AmplifierNonlinearAnalysis.........................................................................................................48SimulationResultsVersusSpecificationRequirements..........................................................49TRLCalibrationKit...........................................................................................................................49FabricatedAmplifierandTRLCalibrationStandards.................................................................53AmplifierLinearS-ParameterMeasurementsUsingTRL........................................................53MeasuredVersusModeled............................................................................................................56Conclusion.......................................................................................................................................60References........................................................................................................................................61ContactAgilent.................................................................................................................BackcoverTableofContents3where:FTisthetotalsystemnoisefactor,F1isthenoisefactorofstageone,F2isthenoisefactorofstagetwo,Fnisthenoisefactorofstagenumbern.g1isthenumericgainfactorofstageone,g2isthenumericgainfactorofstagetwo,gn-1isthenumericgainfactorofthesecondtothelaststage.BasedonEquation1,earliergainstagesdiminishtheeffectofcumulativenoiseaddedbystagesfartherbackinthesystem.Thus,tradingawaytoomuchgainforlowernoisefigureintheearlystagesofthesystemmaydegradetheoverallsystemnoiseduetolessnoise“take-over”ofthefollowingstages.Equations2and3,respectively,convertnoisefigure,NFindB,tonumericno