高通RF-Calibration-介紹課件

RFCalibrationIntroductionRFCalibrationIntroductionAgendaWhatisRFcalibration.Whycalibration.NVitemsofRFcalibration.RxCalibration.TxCalibration.AgendaWhatisRFcalibration.WhatisRFcalibration?RFcalibrationistheprocessofmeasuringdatatobeusedinthe systemforthepurposeofcompensationofnon-linear characteristicsandfrequencyvariations,andtoprovideabsolute powerreferenceandtemperaturecompensationtoensure performanceoftheTxandRxpathsofasubscriberunit.?Outputfromthecalibrationprocessisstoredinnon-volatile(NV) memoryitemsinAMSS.?AMSSusescalibrationvaluesduringnormaloperationtoensure systemperformanceismet.WhatisRFcalibration?RFcalSetup:WhatisRFcalibrationSetup:WhatisRFcalibrationWhycalibrationSubscriberunitshavedifferingRFcharacteristicsDifferencesindesignPart-to-partvariationsofcomponentsofthesamedesignWhycalibrationSubscriberunitIndividualphonesalsochangetheirownRFcharacteristics:

overfrequencychannelovertemperatureWhycalibrationIndividualphonesalsochangeWhycalibrationThesubscriberunitmustestimatetheRxpowerproperlyto maximizesignal-to-noiseratiosandtoprovideabasisforTx poweroutput.ThesubscriberunitmusttransmitatcorrectTxpowerlevelover itslargedynamicrange.TheMobileStationModem?(MSM?)deviceandsystemsoftware combinationmustknowtheRFandanalogcharacteristicsofthe particularunit.FailuretocompensatefordifferingRF/analogcharacteristicsmay causetheunittofailminimumperformancespecificationsWhycalibrationThesubscriberThecompensationvaluesareclassified:StaticRFNVitems:Measuredonceperdesign.CalculatedRFNVitems:RFNVitemsthatarecalculatedbasedonotherparametersofthedesignconfigurations.MeasuredRFNVitems:IsdeterminedbytheRFcalibrationprocess.NVitemsofRFcalibrationThecompensationvaluesareclRxcalibrationPhilosophyofRxAGC(AutomaticGaincontrol)loop.DVGA(DigitalVGA)offsetcalibration.LNA(LowNoiseAmplifier)offsetcalibration.RxcalibrationRxcalibration(RxAGCloop)EachRxchainhasitsownreceiver.?ReceivercalibrationprimarilyconsistsofmeasuringtheDVGAoffset(also calledVGAgainoffset)andmultipleLNAoffsets,allateachchosen frequencyindex.?Softwareloadsthefrequency-compensatedDVGAandLNAoffsetvaluesinto thehardwareregistersshownabove.Rxcalibration(RxAGCloop)EaPhilosophyofRxDVGAoffsetcalibration:Rxcalibration(DVGAoffset)PhilosophyofRxDVGAoffsetcRxcalibration(LNAoffset)PhilosophyofRxLNAoffsetcalibration:Rxcalibration(LNAoffset)PhiRxcalibration(LNAoffset)Rxcalibration(LNAoffset)TxcalibrationPhilosophyofTxAGC(AutomaticGaincontrol)loop.TxLinearizerTxCompensationHDET(Highpowerdetector)TxcalibrationTxcalibration(AGCLoop)ThetransmitterAGCmustadjusttheTxpowerlevelbasedontheRSSI,accessprobeparameters,closed-looppower-controlbits(PCBs),andchannel-configurationattributes.Txcalibration(AGCLoop)ThetTxcalibration(AGCLoop)Txcalibration(AGCLoop)Txcalibration(TxAGCCharacteristic)Txcalibration(TxAGCCharactTxcalibration(TxLinearizer)Txcalibration(TxLinearizer)Txcalibration(TX_GAIN_CTRL.)Txcalibration(TX_GAIN_CTRL.)Txcalibration(HDETFeedbackloopop.)Txcalibration(HDETFeedbackTxcompensation(1/3):NV_BCy_TX_COMP0_I~NV_BCy_TX_COMP3_INV_BCy_TX_COMP0_I=CDMA_TX_COMP_VS_FREQ[15:0]+ CDMA_TX_LIN_VS_TEMP[7:0]+ CDMA_TX_SLP_VS_TEMP[7:0]

Txcalibration(TxComp.)Txcompensation(1/3):NV_BCy_CDMA_TX_LIN_VS_TEMP[7:0]:-UsedtoshifttheeffectiveTx-linearizercurvebyaconstantfortemperature-basedgainchanges.Forexample:Giventemperatureindex,theelementinthistableis0x05,eachofthe36offsetsintheadjustedmastercurvetablewillbeincreasedbyfive,whenthetemperaturecorrespondstothatgivenindex.CDMA_TX_SLP_VS_TEMP[7:0]

-UsedtoshifttheeffectiveTx-linearizercurvebyagraduatedamountfortemperature-basedgainchanges.Ps.typicallyallzerosunlessextraprecisionisdesired.Txcalibration(TxComp.)CDMA_TX_LIN_VS_TEMP[7:0]:TxcHigh-powerdetector(HDET)(1/5):1.OutputatthepowerleveldefinedbyTX_GAIN_CTL.2.TheHDETcircuitmeasurestheoutputpower.3.TheHDETvalueissampled.4.TablethatmapstheHDETvaluetoTxpowerlevel.TheHDET’sestimatedpowerleveliscomparedtoTX_GAIN_CTLtodetermineanerrorvalue.TX_GAIN_LIMITisadjustedbythaterrorvalue.Note:OnlythemaximumpowerlimitisaffectedbytheHDETcircuit.

Txcalibration(TxHDET)High-powerdetector(HDET)(1/HDET(2/5):NV_BCy_TX_LIM_VS_FREQ_I:TheADCreadingsoftheHDETcircuitmayhavesomefrequencydependencies,thisNVitemcanbeusedtocompensateforsuchdependenciesTxcalibration(TxHDET)HDET(2/5):NV_BCy_TX_LIM_VS_FRHDET(4/5):NV_BCy_EXP_HDET_VS_AGC_I:AMSSusesthisNVitemtobuildalookuptable,whichindexesTxpowerestimationviaascaledTX_GAIN_CTL(representingthedesiredTxpower),totheassociatedHDETcircuitvaluesatreferencetemperatureandthereferencefrequency.Procedure:Breakuptheupper1/4ofTX_GAIN_CTLinto16segments.VarythedesiredTxpowerbymanipulatingtheTX_AGC_ADJPDM.ReadthevalueoftheHDETcircuitovereachofthe16segmentsandstoretheresultsinNV_