信号发生器的基本知识概述

SourceBasicsCopyright2000AgendaTypesofsourcesCWSweptSignalGeneratorBlockDiagramsApplicationsSpecificationsSourceBasicsCopyright2000SourcesGenerateSineWavesVoltageTimeVoltageFrequencyThisistheidealoutput:mostspecsdealwithdeviationsfromtheidealandaddingmodulationtoasinewaveRFMicrowaveMillimeter20-50GHz300GHz3-6GHzSpectrumAnalyzerOscilloscopeSourceBasicsCopyright2000TypesofSourcesCW–generatesasinglefrequency,fixedsinewaveSwept–sweepsoverarangeoffrequencies–maybephasecontinuousSignalGenerator–addsmodulation–produces“realworld”signalSourceBasicsCopyright2000AgendaTypesofsourcesCWSweptSignalGeneratorBlockDiagramsApplicationsSpecificationsSourceBasicsCopyright2000CWSourceSpecifications...FrequencyVoltageFrequencyUncertaintyRange:RangeoffrequenciescoveredbythesourceResolution:Smallestfrequencyincrement.Accuracy:Howaccuratelycanthesourcefrequencybeset.EXAMPLEAccuracy==CWfrequency=1GHz=agingrate=0.152ppm/year=timesincelastcalibrated=1year+_fCWtagingcalt**fCWtagingcaltAccuracy=152Hz+_SourceBasicsCopyright2000CWSourceSpecifications...AmplitudeDUTSourceprotectedfromaccidentaltransmissionfromDUTVoltageFrequencyHowaccurateisthisnumber?WhatisPout?WhatisPout?maxminRange(-136dBmto+13dBm)Accuracy(+/-0.5dB)Resolution(0.02dB)SwitchingSpeed(25ms)ReversePowerProtectionSourceBasicsCopyright2000PhaseNoiseResidualFMSpuriousCWSourceSpecifications...SpectralPuritynon-harmonicspur~65dBcharmonicspur~30dBcCWoutputResidualFMistheintegratedphasenoiseover300Hz-3kHzBWphasenoise0.5f0f02f0sub-harmonicsSourceBasicsCopyright2000CWSourceSpecifications...SpectralPurity:PhaseNoiseCWoutputfrequencymeasuredasdBc/HzCh1PMPSD1k10k100kTRACEA:AMarker10000Hz75dBc/Hz-125dBc/HzLogMag5dBc/div-105dBc/HzSourceBasicsCopyright2000RFCWBlockDiagramReferenceOscillatorVCOPhaseDetectorFrac-NdividebyXALCModulatorALCDriverALCDetectorOutputAttenuatorALC=automaticlevelcontrolReferenceSectionSynthesizerSectionOutputSectionSourceBasicsCopyright2000RFCWBlockDiagramReferenceSectionPhaseDetectorOptionalExternalReferenceInputReferenceOscillator(TCXOorOCXO)TCXOOCXOAgingRate+/-2ppm/year+/-0.1ppm/yearTemp.+/-1ppm+/-0.01ppmLineVoltage+/-0.5ppm+/-0.001ppmtosynthesizersectiondividebyXSourceBasicsCopyright2000RFCWBlockDiagramSynthesizerSectionVCOPhaseDetectorFrac-NfromreferencesectiontooutputsectionX2multiplierFrontpanelcontrol5MHz465.5MHzN=93.1931MHz5MHz...producesaccurate,cleansignalsSourceBasicsCopyright2000RFCWBlockDiagramSynthesizerSectionreferenceoscillatorphasenoiseofsourceVCOnoisephasedetectornoisebroadbandnoisefloor20logNphase-locked-loop(PLL)bandwidthselectedforoptimumnoiseperformancePLL/Fractional-N...suppressesphasenoisefrequencySourceBasicsCopyright2000RFCWBlockDiagramOutputSectionALC=automaticlevelcontrolALCModulatorALCDriverALCDetectorOutputAttenuatorfromsynthesizersectionsourceoutputALC–maintainsoutputpowerbyadding/subtractingpowerasneededOutputAttenuator–mechanicalorelectronic–providesattentuationtoachievewideoutputrange(e.g.-136dBmto+13dBm)SourceBasicsCopyright2000mWaveCWBlockDiagramALCDetectorALCModulatorALCDriverOutputAttenuatorSamplerReferenceSectionSynthesizerSectionOutputSectionRefOscVCOPhaseDetFracNbyXVCOPhaseDetectorFrac-NPhaseDetectorTuningCoilsYIGOscillatorSourceBasicsCopyright2000Applications&CriticalSpecificationsLocalOscillator–phasenoise–frequencyaccuracyAmplifierDistortion–spurious–TOI(forsystem)ReceiverTesting–SpuriousspuriouslevelaccuracySourceBasicsCopyright2000Applications&CriticalSpecificationsAsaLocalOscillatorIFsignaltransmitteroutputpoorphasenoisespreadsenergyintoadjacentchannelspoorfrequencyaccuracywillcausetransmittertobeatthewrongfrequencyDUTSourceBasicsCopyright2000Applications&CriticalSpecificationsAmplifierTestingf2f1fU=2f2-f1fL=2f1-f2spurioussignalsfromsourcecancorruptmeasurementfrequencytestsystemthirdorderproductswillalsofallhereoutputRFisolatorf1f2DUTIntermodulationDistortionSourceBasicsCopyright2000Applications&CriticalSpecificationsReceiverTestingIFRejectionCurveFrequencyLevel(dBm)spurfromsourceand/orhighlevelsofphasenoisecancauseagoodreceivertofailsourceoutputIFsignalin-channelsignal(modulatedsignal)out-of-channelsignal(CWormodulatedsignal)DUTReceiverSelectivitySourceBasicsCopyright2000AgilentFamiliesofCWGeneratorsRFMicrowaveAgilent8664/65family100MHz-6GHzLowoutchannelnoiseAM/FM/Pulse.Agilent8662/63family100KHz-2.5GHzLowinchannelnoiseAM/FM/Phase/PulseAgilent83711/12Bfamily10MHz-20GHzCWonlySourceBasicsCopyright2000AgendaTypesofsourcesCWSweptSignalGeneratorBlockDiagramsApplicationsSpecificationsSourceBasicsCopyright2000SweeperSpecifications...Frequencyrampsweep–accuracy–sweeptime–resolutionstepsweep–accuracy–numberofpoints–switchingtimetimef2t2t1f1t4t3t1t2f4f3f1f2SourceBasicsCopyright2000SweeperSpecifications...AmplitudeFrequencySweepLevelAccuracyFlatnessSourceMatch(SWR)PowerSweepPowerSweepRangePowerSlopeRangeSourceMatch(SWR)flatnessspeclevelaccuracyspecf1f2frequencypowerpower}P2P1powersweepranget1t2SourceBasicsCopyright2000Applications&CriticalSpecificationsFrequencyResponse