Broadband Small Signal Amplifier.pdf

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1、BroadbandSmallSignalAmplifierDesignbyTomPierceJHU525.787MMICDesignFall2008AbstractThispaperdescribesthedesignandsimulationofatwostagebroadbandsmallsignalamplifierusingtheTriQuintprocessforMMICfabrication.ThedesignusestwoE-ModepHEMTdeviceswithfeedback

2、toachieveagainof23±1dBfrom2.305GHzto5.785GHz.ThetotalDCpowerconsumptionis19.68mWfromtwo1.5Vsupplies.AllsimulationswereperformedinMicrowaveOfficeversion8.01rbuild4229fromAppliedWaveResearch,Inc.(AWR)withtheTriQuintprocesslibraryversion1.1.21.Introduct

3、ionThisbroadbandsmallsignalamplifierisdesignedforlowpowerandsmallsize.Itcanbeoperatedoffoftwo1.5voltbatteriesdrawing6.56mAeach.Itfitswithina30x60milareaincludingscribelines.EachstageisidenticalwiththesamesizeFETandvoltagedividerbiasnetwork.Thefrequen

4、cyofoperationisfrom2305MHzto5875MHz.Thefrontendoftheamplifierconsistsofalowpassfilterwithacutofffrequencyofabout5.8GHz.NextistheinputmatchingnetworkfollowedbythefirststageFET.Aninterstagematchingnetworksitsbetweenthetwostagesandattheendistheoutputmat

5、chingnetwork(Figure1).InputOutputLowPassInterstageMatchingBiasFETBiasFETMatchingFilterMatchNetworkNetworkFigure1Blockdiagramof2-stagebroadbandamplifierDesignApproachThespecificationsandachievedgoalsforthisdesignareshownbelow(Table1).Allbutoneofthespe

6、cificationshavebeenachievedandthepowerandsizehavebeencutinhalf.TheoutputIP3wasnotmeetduetoanoversightintherequirementsthatwentunnoticeduntilthedesignhadbeencompleted.ParameterSpecificationGoalsFrequency2305to5875MHz2305to5875MHzBandwidth>3575MHz>3575

7、MHzGain(smallsignal)³20dB22dBGainRipple±1dB±1dBOutputIP3>+20dBm+6.9dBmVSWR,50W<1.5:1input&output<1.5:1input&outputSupplyvoltage+3.3V+1.5VSize60x60milANACHIP30x60milFETsize4x154x15Table1Designspecificationsandachievedgoals.Thefirststepofthisdesignisto

8、determinethetypeofFETtouse.TheEmodePHEMPTprovideshighergainthantheDmodeatthesamepowerwithlessnoise.TheEmodeisalsobiasedwithapositivegatevoltage,whichwillmakethebiasnetworkdesignsimpler.Withthetypeandsizeofthedeviceknown,anIVcurvetraceisgeneratedtodet