AN-GT111A-Boosting_RF_Output_Power 电路图.pdf

《AN-GT111A-Boosting_RF_Output_Power 电路图.pdf》由会员分享，可在线阅读，更多相关《AN-GT111A-Boosting_RF_Output_Power 电路图.pdf（2页珍藏版）》请在收音机爱好者资料库上搜索。

1、 ANGT111ABoostingRFOutputPower Copyright 2010 Giga-tronics Incorporated. All rights reserved. AGigatronicsApplicationnoteANGT111A BoostingRFOutputPowerSignalGeneratorHighPowerOptionsversus ExternalPowerAmplifiers Youneedhigherpowertodriveyourdeviceorantenna.Shouldyouchoosethehighpoweroptiontoa micro

2、wavesignalgeneratororoptforanexternalpoweramplifierinstead?Thetradeoffsarenot alwaysobvious.Whileaddingthehighpoweroptiontoamicrowavesignalgeneratormayseemaneasy solution,rememberthatthetradeoffsareusuallyincreasedharmonicsandIMD,aswellasthepractical limitstohowmuchpowercanbeadded. Choosinganexterna

3、lamplifierusuallyresultsinbetteroverallperformance,withbettersignalpurity andhigherpowerlevelsavailable.Signalpurityandverylinearamplificationarecriticalformodulated signalsandthatoftenrequiresoperatingbackedofffromthemaximumpowerlevels.Usinganexternal poweramplifierwithhigherpowerallowsmoreheadroom

4、tobackoff,forhighcrestfactorsignals. Anadditionaladvantageofusinganexternalamplifieristhatitprovidesyouwiththeabilityto physicallypositiontheamplifierclosertothedeviceundertest(DUT)orantenna.Byplacingthe amplifierclosertotheDUT(orantenna),youmaybeabletoreducecableslossesandachievehigher powersattheD

5、UT.Sincemostexternalamplifiershaverelativelyhighgain,movingthecablelossto betweenthesignalgeneratorandtheamplifierratherthanbetweentheamplifierandDUTachievesthe desiredresults. CloseproximitytotheDUT(orantenna)mayalsoreducethemagnitudeofrippleandstandingwavesin thecablingiftheimpedancematchtotheDUTo

6、rantennaisnotgood.Boththeeffectsofcablelossand mismatchreflectionsbecomemoreproblematicasthefrequenciesincrease.Theseeffectsmaybe minimizedbymovingthelongcabletobetweensignalgeneratorandamplifier(wherethematchis better,reducingreflections)andkeepingthecablelengthshortbetweenamplifierandDUTtominimize

7、 thestandingwaves. GT-1000A 20 GHz Microwave Power Amplifier and 2520B Microwave Signal Generator RadioFans.CN 收音机爱 好者资料库 ANGT111ABoostingRFOutputPower Copyright 2010 Giga-tronics Incorporated. All rights reserved. AGigatronicsApplicationnoteANGT111A Itsalsoimportanttoconsiderthepriceperformancetrad

8、eoff.Highpoweroptionstomicrowavesignal generatorscanbeveryexpensive,over$40Kinsomecases,whileanexternalmicrowavepower amplifiermaybeconsiderablylessexpensive,aswellasprovidinghigherpowerandlowerharmonics. Harmonicsareafunctionofpowerlevel.Whilea“1Watt”highpoweroptiontoamicrowavesignal generatormayha

9、veharmoniclevelsof25dBcat+25dBm,alessexpensive“10Watt”external microwavepoweramplifiercouldhaveharmoniclevelsof35dBcatthesame+25dBm(andsame frequency)becauseitsoperatingwellbelowitsmaximumoutputpower. Anadditionalconsiderationissafetyandthepreventionofhighpowerlevelscausingdamagetothe DUT.Usinganext

10、ernalmicrowavepoweramplifierallowstheusertoactivatethehighpoweronlywhen needed.Thesignalgeneratorcanbeturnedonandsetuppriortoturningonthehighpower.While somemicrowavesignalgeneratorstrytocompensatebyofferingapowerclampcapability,itis importanttorememberthattheremaybeadelayofmanymicrosecondsbeforethe

11、powerclampcan respond,allowingapotentiallydamagingpulsetooccur.PowerclampsaredesignedforCWoperation andmaybeofnopracticaluseinnarrowpulsedmodeapplications. Lastly,ifthepoweramplifierfails,withthesignalgeneratoroptionyouvelostuseofthecomplete signalgenerator;obviouslynotaconcernwiththeexternalpoweramplifierapproach. Forthesereasons,Gigatronicshaschosentoofferexternalmicrowavepoweramplifierstocomplement ourmicrowavesignalgenerators,includingtheGT1000AandGT1050Amicrowavepoweramplifiers. GT-1050A 50 GHz Microwave Power Amplifier and 2550B Microwave Signal Generator RadioFans.CN 收音机爱 好者资料库