文档介绍：DDSFREQUENCYGENERATORJonathanHull&KentWarnerSeniorDesign,,:,andappropriateperspecifications,:BlockDiagram:TechnologyChoices:MicroprocessorAVR8535Micro40pinsforversatilefunctionalitywithattenuationlinesInternal1MHzoscillator+5VsupplyfromconstructedpowersupplyUsedtopowertheDDSchip,Attenuator,municationDirectDigitalSynthesis(DDS)AD9851DDSInexpensive,mainstreamDDSoptionOptionof6Xreferenceclockmultiplier0-90MHzoutputfrequencyrange(withreferenceclockof180MHz)parator,RS232chiponboardConfiguration:4800Baud8DataBits1StopBitAmplificationLM7171OperationalamplifiersGainBandwidthà200MHz+/-<50mOhm+5VneededtoswitchviacoilCostfeasibleat$2perrelay0–69dBattenuationrangeSeeconstructioninstructionsforappropriateresistorvaluesOutputBufferLM7171OperationalAmplifier+/-5VoperationHighspeed,highoutputcurrentPowerSupplyTriadVPP24-830TransformerSize/Costfeasible7805/7905VoltageregulatorsProperoutputvoltageRelevantStandards:puterandmicroprocessorSystemDesign:DDSConfiguration/Design: R_SET: