《低噪声放大器简介》PPT课件.ppt

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1、Low-NoiseAmplifierRFReceiverBPF1BPF2LNALOMixerBPF3IFAmpDemodulatorAntennaRFfrontendLow-NoiseAmplifierFirstgainstageinreceiverAmplifyweaksignalSignificantimpactonnoiseperformanceDominateinput-referrednoiseoffrontendImpedancematchingEfficientpowertransferBe

2、tternoiseperformanceStablecircuitLNADesignConsiderationNoiseperformancePowertransferImpedancematchingPowerconsumptionBandwidthStabilityLinearityNoiseFigureDefinitionAsafunctionofdeviceG:PowergainofthedeviceNFofCascadedStagesOverallNFdominatedbyNF1[1]F.Fri

3、is,“NoiseFigureofRadioReceivers,”Proc.IRE,Vol.32,pp.419-422,July1944.Sin/NinG1,N1,NF1Gi,Ni,NFiGK,NK,NFKSout/NoutSimpleModelofNoiseinMOSFETFlickernoiseDominantatlowfrequencyThermalnoiseg:empiricalconstant2/3forlongchannelmuchlargerforshortchannelPMOShasles

4、sthermalnoiseInput-inferrednoiseVgIdViNoiseApproximationThermalnoise1/fnoiseBandofinterestFrequencyNoisespectraldensityThermalnoisedominantPowerTransferandImpedanceMatchingPowerdeliveredtoloadMaximavailablepowerRsVsjXsjXLRLIVImpedancematchingLoadandsource

5、impedancesconjugatepairRealpartmatchedto50ohmAvailablePowerEqualpoweronloadandsourceresistorsReflectionCoefficientRsVsjXsjXLRLIVReflectionCoefficientNoreflectionMaximumpowertransferS-ParametersParametersfortwo-portsystemanalysisSuitablefordistributiveele

6、mentsInputsandoutputsexpressedinpowersTransmissioncoefficientsReflectioncoefficientsS-Parametersa1b1b2a2S11S12S22S21S-ParametersS11–inputreflectioncoefficientwiththeoutputmatchedS21–forwardtransmissiongainorlossS12–reversetransmissionorisolationS22–output

7、reflectioncoefficientwiththeinputmatchedS-ParametersSZ1Z2Vs1Vs2I1V1I2V2StabilityConditionNecessaryconditionwhereStableiffwhereAFirstLNAExampleAssumeNoflickernoisero=infinityCgd=0ReasonableforappropriatebandwidthEffectivetransconductanceRsVsVsRs4kTRsVgsgmV

8、gs4kTggmioPowerGainVoltageinputCurrentoutputNoiseFigureCalculationPowerratio@outputDevicenoise+input-inducednoiseInput-inducednoiseUnityCurrentGainFrequencyDeviceioutiin0dBfTAiffrequencySmall-SignalModelofMOSFETCgsC