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Features•VeryLowPowerDesign(40mW)SingleIFArchitectureExcellentNoisePerformance1.5-bitADCOnChipSmallQFNPackage(4mm×4mm,24pins)Highlyintegrated,FewExternalComponentsAdvancedBiCMOSTechnology(UHF6s)RoHSCompliant1.DescriptionTheATR0601isasingleIFGPSfront-endIC,designedtomeettherequirementsofmobileandautomotiveapplications.ExcellentRFperformancecombinedwithlownoisefigureenableshighqualityGPSsolutionsandit'sverylowpowerconsumptionfitsperfectlytoportabledevices.Fea-turingabalancedXTOandafullyintegratedbalancedfrequencysynthesizer,onlyfewexternalcomponentsarerequired.TheATR0601offersacompleteautonomousmode,utilizingtheonchipAGCinclosedloopoperation,tosetthegainoftheIFVGA.Alternatively,incombinationwiththeAntaris™4basebandprocessorfamily,theopti-mumgainoftheIFVGAcanbecomputedandsetbysoftware,usingthedigitalSDIinterface.Figure1-1.BlockDiagramXTOPMSSLogicDAVCOPLLDABPITESTMOGNDNBPIBPNBPVCCVCCVDIGPUXTOPURFRFNRFXTONXTOXNXSDISLSHSCAGCOEGC≥1GPSFront-endICATR06014866G–GPS–11/0624866G–GPS–11/06ATR06012.PinConfigurationFigure2-1.PinningQFN24123456181716151413789101112242322212019PaddleGNDVDIGAGCONXTONXXXTOPURFPUXTONBPIBPINBPBPVCCMOTESTNRFRFNCSCSHSLSDIEGCVCCTable2-1.PinDescriptionPinSymbolType(1)FunctionPaddleGNDSCommonground1VDIGSDigitalsupply2AGCOA_I/OAGC:gaincontrolvoltageoutput/cornerfrequencydetermination3NXTOA_IXTOinterface(optional:TCXOinput)4NXA_OXTOinterface5XA_OXTOinterface6XTOA_IXTOinterface(optional:TCXOinput)7VCCSAnalogsupply8MOA_OTestbufferoutput(fIF)9TESTA_IEnabletestbuffer10NRFA_IRFinputcomplementary11RFA_IRFinput12NC–Notconnected13BPA_OIF-Filterinterface(mixeroutput,opencollector)14NBPA_OIF-Filterinterface(mixeroutputcomplementary,opencollector)15BPIA_IIF-Filterinterface(IF-input)16NBPIA_IIF-Filterinterface(IF-inputcomplementary)17PUXTOD_IPower-upXTO18PURFD_IPower-upRF19VCCSAnalogsupply20EGCD_IEnableexternalgaincontrol(high=external;low=internal)21SDID_IInputforexternalgaincontrolsignal(Σ∆modulation)22SLD_ODataoutput:“low”23SHD_ODataoutput:“high”24SCD_OSampleclockNote:1.Type:A_IAnaloginput,A_OAnalogoutput,D_IDigitalinput,D_ODigitaloutput,SSupply34866G–GPS–11/06ATR06013.FunctionalDescription3.1GeneralDescriptionTheATR0601GPSreceiverIChasbeenespeciallydesignedforGPSapplicationsinbothmobilephoneandautomotiveapplications.Fromthissystempointofview,itincorporateshigh-estisolationbetweenGPSandcellularbands,aswellasverylowpowerconsumption.TheL1inputsignal(fRF)isaDirectSequenceSpreadSpectrum(DSSS)signalwithacentrefre-quencyof:fRF=1575.42MHz.ThedigitalmodulationschemeisBi-Phase-Shift-Keying(BPSK)withachiprateof1.023Mbps.Astheinputsignalpowerattheantennaisapproximately–140dBm,thedesiredsignalisbelowthethermalnoisefloor.3.2PMSSLogicThePowerManagement,StartupandShutdownLogicensuresreliableoperationwithintherec-ommendedoperatingandtimingconditions.TheexternalpowercontrolsignalsPUrfandPUxtoarepassedthruSchmitt-triggerinputs,digitalandanalogsupplyvoltagesareanalyzedbymoni-toringcircuits.3.3XTOTheXTOisdesignedforminimumphasenoiseandfrequencyperturbations.Thebalancedtopologygivesmaximumisolationfromexternalandgroundcouplednoise.Thebuilt-injumpstartcircuitryensuresreliablestart-upbehaviourofanyspecifiedcrystal.Forusewithanexter-nalTCXO,theXTOcircuitrycanbeusedasasingle-endedorbalancedinputbuffer.Therecommendedreferencefrequencyis:fXTO=23.104MHz.3.4VCO/PLLThefrequencysynthesizerfeaturesabalancedVCOandafullyintegratedloopfilter,thusnoexternalcomponentsarerequired.TheVCOcombinesverygoodphasenoisebehaviourandexcellentspurioussuppression.Therelationbetweenthereferencefrequency(fXTO)andtheVCOcentrefrequency(fVCO)isgivenby:fVCO=fXTO×64=23.104MHz×64=1478.656MHz.3.5RF-Mixer/Image-filterCombinedwiththeantennaanexternalLNAprovidesafirstband-passfilteringofthesignal.FortheLNA,Atmel’sATR0610isrecommended,duetoit’slowNoiseFigure,highlinearityanlowpowerconsumption.TheoutputoftheLNAdrivesanSAWfilter,whichprovidesimagerejectionforthemixerandtherequiredisolationofallGSMbands.TheoutputoftheSAWfilterisfedintoahighlylinearmixerwithhighconversiongainandexcellentnoiseperformance.TheIFfrequency(fIF)isgivenby:fIF=fRF–fVCO=1575.42MHz–1478.656MHz=96.764MHz.3.6IF-filterThemixerdirectlydrivesanexternalLCband-passfilterviaopencollectoroutputs.Inordertoprovidehighestselectivityandconversiongain,itisrecommendedtodesigntheexternalfilter,accordingtotheapplicationproposal,asa2-polefilterwithaqualityfactorQ25.44866G–GPS–11/06ATR06013.7VGA/AGCTheoutputoftheIF-Filterdrivesanon-chipVariableGainAmplifier(VGA)whichiscombinedwithadditionallow-passfiltering.Theon-chipAutomaticGainControl(AGC)stagesetsthegainoftheVGAinordertooptimallychargetheinputofthefollowinganalog-to-digitalconverter.TheAGCcontrolloopcanbeselectedforon-chipclosedloopoperationorforexternalgaincontrolmode.Forexternalgaincontrolmode,theloopneedstobeclosedbythebasebandICATR0621.3.8A/DConverterTheanalog-to-digitalconverterstagehasatotalresolutionof1.5bit.Itcomprisesbalancedcom-paratorsandasubsamplingunit,clockedbythereferencefrequency(fXTO).Thefrequencyspectrumofthedigitaloutputsignal(fOUT),presenta