Microwave monolithic integrated circuit development for future spaceborne phased array antennas

MICROWAVEMONOLITHICINTEGRATEDCIRCUITDEVELOPMENTFOR FUTURESPACEBORNEPHASEDARRAYANTENNASG. Anzic,T. J.Kascak,A.N. Downey,D.C. Liu,and D. J.ConnollyNationalAeronauticsandSpaceAdministrationLewisResearchCenterCleveland,Ohio44135Abstract TorranceResearchCenter (HAC-TRC)and HoneywellCorporateTechnologyCenter(H-CTC). The receiveThe developmentof fullymonolithicgallium module'sperformancegoalsare listedinTable1.arsenide(GaAs)receiveandtransmitmodulessuit- The module'sfinalconfiguration,consistingofableforphasedarrayantennaapplicationsinthe four functionalsubmodulesintegratedon a single30/20 gigahertzbandsispresented. Specifications chip iSshown inFig. 1. Basictechnologiesem-andvariousdesignapproachestoachievethe design ployedinthefabricationincludesub-microngategoalsaredescribed. Initialdesignandperfor- lengthfieldeffecttransistor(FET)fabricationmanceof submodulesandassociatedactiveand pas- usingrefractorymetalizationsystems,ion implan-sive componentsarepresented. A tradeoffstudy tationfor lownoise amplificationandmicrostripsummaryispresentedhighlightingtheadvantages circuitryfabricatedon semi-insulatinggalliumof distributedamplifierapproachcomparedtothe arsenide(GaAs)substrate.conventionalsinglepowersourcedesigns.Sincethe receivemodule'sintendedapplica-Introduction tion isfor steerablephasedarrayantennaswherea largenumberofreceive- transmitelements isStudieshave identifiedtheuseofmultiple employed,a possibleelementmightbe awaveguidescanningbeamantennasystemsas amajorfactor in radiator. Figures2 and3 showa proposedmoduleachievingminimumcostandefficientuse of the layoutand itspossibleincorporationinawave-frequencyandorbitalresourcesforthefuture guideradiator (fixture)employingsuitablewave-generationof thecommunicationssatellitesystems, guidetomicrostriptransitions_with controlTheAdvancedCommunicationsTechnologySatellite and powerconnections.(ACTS),scheduledfor launchinthelate 1980'swill employthescanningbeam antennatechnology Low NoiseAmplifierSubmodule(LNA1in the20/30gigahertzbandstomaximizetheoperatingefficiency. Futurecommunications The designand fabricationapproacheschosensatellitesystemsmayusemonolithicreceiveand byboth contractorsinthe developmentof the lowtransmitmoduletechnologywhich isexpectedto noiseamplifiermodulesare similar. Sub half-furtherincreasethesystemoperatingefficiency, microngate lengthFET'shave been designedandIn supportofthedevelopmentof advancedantenna are inprocessof fabricationfor use inthe lowconcepts,a keyareatherefore,isthedevelopment noise amplifiers. Bothconventionalphoto-of compatiblemonolithicreceiveandtransmit lithographysupplementedby the E-beamlithographymodulesat theabovestatedfrequencies, are usedfor circuitand activecomponentfabrica-tion. SinceLNA submodulesare still inthe finalGalliumarsenide(GaAs)monlithicmicrowave design andearlyfabricationstages,only prelim-integratedcircuits(MMIC) offersubstantialper- inarytestresultsare available. Figure4 showsformanceadvantagesintheproposedfrequenciesof the HughesLNA design,itscalculatedcharacteris-interest. Sinceentiremicrowavecircuitscan be ticsand componentlayout. Significantlybetterfabricatedon a singlechip,utilizingdeposition, resultsare expectedinthe FET gain and noiseper-epitaxyandionimplantationtechniques,the re- formanceareasinthe future. Typicallownoisesultingcircuitisfree ofparasitics,lossesand FET performanceinthe bandof interestisexpectedcomponentvalueuncertaintiesnormallyassociated to improvebyapproximately1 dBduringthe dura-with wire bondsandotherexternalinterconnects, tionofthis developmenteffort. Consequently,Monolithiccircuitscanthereforebedesigned, the modulenoisefiguregoalof 5 dBor less isdevelopedandproducedforoptimumperformance expectedtobe achievedwithoutdifficulty.with no circuitadjustmentsafterassembly. Figure5 showsthe initialamplifierdesignem-ployedbyHoneywell. A singlegateFET versionofInadditiontomonolithiccircuitperformance the amplifierisexpectedtobe used inthe LNA.advantagesmentioned,additional,very attractive Noiseperformanceissimilarto the Hughesversionadvantagesareofferedbymicrowavemonolithic describedabove.integratedcircuitsinareasofcost,weightperfunctionandreliability. As technologymatures PhaseShifterSubmoduleand substantialvolumesof productionareachieved,alladvantageswill bemore fullyrealized. Possiblythe most challengingpartof theproposedeffortto developamonolithicreceiveNASA LewisResearchCenterispursuingthe module isthe developmentof the phaseshifterfollowingMMIC developmentswhichpromisemaximum submodule.The performancegoalsofthe submoduleimpactforthefuturecommunicationssystemsin requireitsoperationatfive differentphasethe30/20GHz frequencyrange, statesbetweenzero and 180degreescontrolledbya digitalinputsignal. The phase shifteristo30 GHzMonolithicReceiveModule use a truetimedelayphase shiftscheme,where inany stateof the phaseshifterthe totalmoduleTwo paralleleffortsto developa 30GHz mono- phaseshiftisproportionaltofrequencywithinlithicreceivemoduleareinprogressatHughes- the 27.5 to30 gigahertzpassband.