MAXIM卫星STB调谐器解决方案-技术方案

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MAXIM公司的MAX2112是低成本的直接变换调谐器,它为卫星机顶盒(STB)和VSAT应用而设计,适合8PSK和数字视频广播(DVB-S2)应用.采用宽带I/Q下变换器,MAX2112能把LNB中的卫星信号直接转换成基带.工作频率从925MHz到2175MHz.MAX2112包括LNA和可变增益RF放大器,I和Q下变换混频器,有可编程截止频率的基带低通滤波器以及数控的基带可变增益放大器.解决方案包括MAX2112的主要性能,应用领域和方框图以及典型的应用电路图.

TheMAX2112low-cost,direct-conversiontunerICisdesignedforsatelliteset-topandVSATapplications.TheICisintendedfor8PSKandDigitalVideoBroadcast(DVB-S2)applications.

TheMAX2112directlyconvertsthesatellitesignalsfromtheLNBtobasebandusingabroadbandI/Qdownconverter.Theoperatingfrequencyrangeextendsfrom925MHzto2175MHz.

ThedeviceincludesanLNAandanRFvariable-gainamplifier,IandQdownconvertingmixers,andbasebandlowpassfilterswithprogrammablecutofffrequencycontrolanddigitallycontrolledbasebandvariable-gainamplifiers.

Together,theRFandbasebandvariable-gainamplifiersprovidemorethan80dBofgaincontrolrange.TheICiscompatiblewithvirtuallyallDVB-S2demodulators.

TheMAX2112includesfullymonolithicVCOs,aswellasacompletefractional-Nfrequencysynthesizer.Additionally,anon-chipcrystaloscillatorisprovidedalongwithabufferedoutputfordrivingadditionaltunersanddemodulators.Synthesizerprogramminganddeviceconfigurationareaccomplishedwitha2-wireserialinterface.

TheICfeaturesaVCOautoselect(VAS)functionthatautomaticallyselectstheproperVCO.Formultitunerapplications,thedevicecanbeconfiguredtohaveoneoftwo2-wireinterfaceaddresses.Alow-powerstandbymodeisavailablewhereuponthesignalpathisshutdownwhileleavingthereferenceoscillator,digitalinterface,andbuffercircuitsactive,providingamethodtoreducepowerinsingleandmultitunerapplications.

TheMAX2112isthemostadvancedDBStuneravailabletoday.ThelownoisefigureeliminatestheneedforanexternalLNA.AsmallnumberofpassivecomponentsareneededtoformacompleteDVB-S2RFfrontendsolution.Thetunerisavailableinaverysmall28-pinthinQFNpackage.

主要特性:

925MHzto2175MHzFrequencyRange

MonolithicVCO

LowPhaseNoise:-97dBc/Hzat10kHzNoCalibrationRequired

HighDynamicRange:-75dBmto0dBm

IntegratedVariableBWLPFilters:4MHzto40MHz

Single+3.3V±5%Supply

Low-PowerStandbyMode

Multiple2-WireAddressesforMultitunerApplications

DifferentialI/QInterface

I2C2-WireSerialInterface

VeryS