TheAD8320isadigitallycontrolledvariablegainamplifieroptimizedforcoaxiallinedrivingapplications.An8-bitserialworddeterminesthedesiredoutputgainovera36dBrange(256gainlevels).TheAD8320provideslineargainresponse.

TheAD8320ismadeupofadigitallycontrolledvariableattenuatorof0dBto–36dB,whichisprecededbyalownoise,fixedgainbufferandfollowedbyalowdistortionhighpoweramplifier.TheAD8320hasa220ohminputimpedanceandacceptsasingle-endedinputsignalwithaspecifiedanaloginputlevelofupto0.310Vp-p.Theoutputisspecifiedfordrivinga75ohmload,suchascoaxialcable,althoughtheAD8320iscapableofdrivingotherloads.Distortionperformanceof–57dBcisachievedwithanoutputlevelupto12dBm(3.1Vp-p)at42MHz,while–46dBcdistortionisachievedwithanoutputlevelupto18dBm(6.2Vp-p).

AkeyperformanceandcostadvantageoftheAD8320resultsfromtheabilitytomaintainaconstant75ohmoutputimpedanceduringpower-upandpower-downconditions.Thiseliminatestheneedforexternal75ohmback-termination,resultingintwicetheeffectiveoutputvoltagewhencomparedtoastandardoperationalamplifier.Additionally,theon-chip75ohmterminationresultsinlowglitchoutputduringpower-downandpower-uptransitions,eliminatingtheneedforanexternalswitch.

TheAD8320ispackagedina20-leadSOICandoperatesfromasingle+5Vthrough+12Vsupplyandhasanoperationaltemperaturerangeof–40°Cto+85°C.

Anevaluationboardisavailableforthisproductandmaybeorderedusingthefollowingproductnumber:AD8320-EB.Schematicandlayoutforthisevaluationboardiscontainedintheproductdatasheet.