TheAD9879isasinglesupplyCableModem/SetTopBoxMixedSignalFrontEnd.Thedevicecontainsatransmitpathinterpolationfilter,acompletequadraturedigitalupconverterandtransmitDAC.Thereceivepathcontainsa12-bitADC,a10-bitADC,andDual7-bitADCs.AllinternallyrequiredclocksandanoutputsystemclockaregeneratedbythePLLfromasinglecrystalorclockinput.

TheAD9879isanevolutionaryproductintheMxFEproductportfolio,itisthenextgenerationofthehighlysuccessfulAD9873.TheAD9879featuresalowerpriceandseveralfunctionalimprovementswhencomparedtotheAD9873.Theseimprovementsincludelowerpowerconsumption,improvedIFunder-samplingcapability,outputgaincontrolin.5dBstepsallowingtheuseofcoarsegainoutputdrivers,andimprovedtuningresolution;3.2Hzresolutionisprovided.Inaddition,the8-bitADCshavebeenreplacedwith7-bitdevicestoreducecostwhilestillprovidingsufficientperformancefortheout-of-bandchannelI&Qdemodulation.

Thetransmitpathinterpolationfilterprovidesanupsamplingfactorof16xwithanoutputsignabandwidthashighas8.3MHz.Carrierfrequenciesupto65MHzwith26bitsoffrequencytuningresolutioncanbegeneratedbythedirectdigitalsynthesizer(DDS).ThetransmitDACresolutionis12bitsandcanrunatsamplingratesashighas232MSPS.Analogoutputscalingfrom0to7.5dBin0.5dBstepsisavailabletopreserveSNRwhenreducedoutputlevelsarerequired.

The12-bitand10-bitIFADCscanconvertdirectIFinputsupto70MHzandrunatsampleratesupto33MSPS.Avideoinputwithanadjustablesignalclampinglevelalongwiththe10-bitADCallowtheAD9879toprocessanNTSCandaQAMchannelsimultaneously.

TheprogrammablesigmadeltaDACcanbeusedtocontrolexternalcomponentssuchasvariablegainamplifiers(VGAs)orvoltagecontrolledtuners.TheCAPORTprovidesaninterfacetotheAD8321/AD8323orAD8322/AD8327programmablegainamplifier(PGA)cabledriversenablinghostprocessorcontrolviatheMxFESPORT.

TheAD9879isavailableina100-pinMQFPpackage.Itoffersenhancedreceivepathundersamplingperformanceandlowercost,comparedwiththepincompatibleAD9873.TheAD9879isspecifiedoverthecommercial(-40ºCto+85ºC)temperaturerange.