射频芯片校准设计

1RFIC/IMS2008WSB-3©AryaBehzadRFIC/IMS2008WSB-3©AryaBehzadWSL-3CalibrationTechniquesforWirelessSoCsAryaBehzadBroadcomCorporationSanDiego,CA2RFIC/IMS2008WSL-3©AryaBehzadOutline•WhyCalibrate?•CalibrationTechniques–ResistorCalibration–RCTimeConstantCalibration–VCOCalibration–AutomaticFrequencyControl(AgileFrequencyOffsetCalibration)–QuadratureErrorandLOFeedthroughCalibration–LOGenerationAmplitudeControlSystemandCalibration–OtherCalibrations•ProcessSensingandCalibration•TemperatureSensingandCalibration•PowerDetectorCalibration3RFIC/IMS2008WSL-3©AryaBehzadCalibrations&“Support”Circuitry•Radioself-calibrationsusedtobeconsideredas“nicetohave”.Todayradioself-calibrationshavebeenrecognizedasabsolutelyessential.•Designofthecalibrationalgorithmsandmethodologyisanintegralpartoftheradiodesign,andnotanafter-thought•Chiplevelandsystemlevelauto-calibrationisrequiredforovercomingdifficultiesofintegratedradiodesign,increasingchipandsystemyieldandimprovingperformance.•Someexamples:•VCOtuning•TxandRxIQCalibration•R-Calibrationonbandgapblocks•RCtimeconstantcalibration•RSSIs•Agilecenterfrequencycorrection•Integratedtemperaturesensor•TransmitLOfeedthroughcancellation•TSSI•RxDCOffsets&High-PassCorners•Processsensing4RFIC/IMS2008WSL-3©AryaBehzadToday’sRadio/RFTechnology•MultipleFrequencyBands,SimultaneousOperationformultiplestandards&Applications(WLAN,Bluetooth,RFID,…)•RapidRealTimeconfiguration/calibration:–OptimumPerformances–Max/BestYields–MultipleFab/Process,Package–NoFactoryCalorPre-StoredCaldataneeded,NoFlashorSRAM–ReduceRFtesttime–Compensateovertemperature(whichfactory-caldoesnotallowfor)DSPProcessorProgramming/CalibrationBasebandPLL/LOGENAFERXAnalogRXAFETXAnalogTXRFRXRFFERFTXPARFFE5RFIC/IMS2008WSL-3©AryaBehzad•RadioBlocksaredevelopedusingadigitallycontrollablematrixof–Passivedevices(R,L,C)–Activesdevices–ADCs&DACs–SmallControllers/DSPsRadioCalibrationTechnologySwitchingResistor&CapacitorsIT/RcontrolGainsettingLNAcontrolDigitalLogicBlockADCDACDACDACOpenloopClosedLoop6RFIC/IMS2008WSL-3©AryaBehzadIntegratedSmartRadioTechnologyLOGenerationPLLFracNAutomaticCalibrationControlandDataInterfaceRFInputRFOutputControlI/QOutputI/QInput•RadioBlocksaredevelopedusingadigitallycontrollablematrixofPassivedevices,Activesdevices,ADCs&DACs&SmallControllers/DSPs–Theseunitscanbedigitallyprogrammed/calibratedbylocalcalibrationEngines–Theseunitscanbedigitallyprogrammed/calibratedthroughJTAGbybaseband•LongTermAgile/RealTimecalibration–OptimizesoverallperformancesovermanyframesorPackets•ShortTermCal,Optimizesoverallperformancesoveraframeorpacket–Accuratefrequencyresponse,centerfrequency,gain–Maximumdynamicrange–Minimizingnon-idealities,suchasDCoffsets,I/Qmismatches,feed-through,coupling…7RFIC/IMS2008WSL-3©AryaBehzadReceiverArchitecturew/Calibration•BandwidthandfrequencyresponsearesetbyprogrammingR*C•GainandcurrentconsumptionaresetbyprogrammingI*R•RXDCoffsetandblockingcanbecalibratedgloballyandlocallyLOI1GWRSSIOutIQLOQ1GDCOffsetCancellerAUnitdBmRFAtt20dBRefLvl-15dBmRefLvl-15dBmStart0HzStop300kHz30kHz/RBW5kHzVBW2kHzSWT76ms2MA3MA1MA1VIEW2VIEW3VIEW4VIEW4MA-65-60-55-50-45-40-35-30-25-20-15Date:12.FEB.200203:28:5979x100001101default79x1001100179x10010001RC&LCCalibration8RFIC/IMS2008WSL-3©AryaBehzadMulti-BandTransmitterw/Calibration•Outputlevelcalibration•LOLeakageCalibration•Gaincalibration•Bandwidth&frequencycalibration/programmingLOI2GLOQ2GLOI5GLOQ5GAnalogInIQTSSI&PeakDetectorRC&LCCalibration0123456789101112131415Register52WriteMeasuredDataoncornerlot(ExistingWLAN)-50.0-45.0-40.0-35.0-30.0-25.0-10.0-15.0-10.0LOLeakage(dBc)DACbiasisadjustedtocreateDCoffsetforLOLeakageCal9RFIC/IMS2008WSL-3©AryaBehzad90o++TRANSCEIVERCHIPDIGITALBASEBANDCHIP/HOSTDACDACADCADCDAC90oDACDACDACDACDACCalibrationatpower-uporbetweenframes–Useloop-backpathsDigitalcorrection:–I/Qmismatch–LOleakageAnalogcorrection–DCoffset–FiltercutoffRef:I.Bouras,etal,ISSCC2003ExampleofTransceiverwithMultipleCalibrations10RFIC/IMS2008WSL-3©AryaBehzadRequirementsforWLANTransmitters•Lowtransmiterrorvectormagnitude(EVM).–Highlinearity.–SmallI/Qimbalance.–Lowlocaloscillator(LO)phasenoise.•Lowlocaloscillatorfeed-through(LOFT).–-15dBrforIEEE802.11astandard.•Wideandaccurategain-controlrange.–Ratedependentpowercontrol.11RFIC/IMS2008WSL-3©AryaBehzadSourcesofLOFTinTx•BBLOFT–Deviceoffsetsup-convertedtoRF.•RFLOFT–MismatchintheGilbertcellmixerswitchingquads.–Parasiticcapacitancecoupling.–Mutualinductancecoupling.RFPGAPADLOILOQBB_IBB_QGmGmLPFLPFDACDACoffsetsoffsetsoffsetsoffsetsoffsetsoffsetsParasiticcouplingRFParasiticcouplingLOFT12RFIC/IMS2008WSL-3©AryaBehzadSourcesofI/QImbalanceinTx•BasebandI/Qimbalance–DeviceandbiasmismatchesbetweenIandQpaths.•RFI/Qimbalance–LOI/Qmismatch.–MixerI/Qmismatch.RFPGAPADLOILOQBB_IBB_QGmGmLPFLPFDACDACRFIQPerfectI/QI/QImbalance13RFIC/IMS2008WSL-3©AryaBehzadTx:IQmodulatorimpairments•Exampleoutputspectrum–BBinputissingletoneinquadratureat1MHz;LOis5.500GHz•3rdorderterm•UndesiredSB•Carrier•Desiredsignal•BBHD2•BBHD314RFIC/IMS2008WSL-3©AryaBehzadRx&Tx:IQBalance&ImageRejection•Quadraturegaina