(DOC)基于新颖宽带肖特基二极管模型的毫米波平衡式混
频器设计英文
基于新颖宽带肖特基二极管模型的毫米波
平衡式混频器设计(英文)
第30卷第5期
2011年1O月
红外与毫米波
J.InfraredMillim.Wave s
Vo1.30.No.5
October,2011
文章编号:1001—9014(2011)05—0385—04
Millimeter. .wavebalancedmixerbasedonanovelwide-.bandSchottkydiodemodel
MO UJin—Chao.LVXin,YUWei—HuafSch0o1 ofInformationandElectronics,BeijingInstituteofTechnology,Beijing100081,China)
Abstract:ASchottkydiodemodelforthemixerothephysicalstru.tureoftheSchottkydiode.anove13Delectromagnetic(EM)modelwasbuiltandanalyzedbyfiniteelementmethod-Awide’ bandequivalentcircuitupt0110GHzwasproposedtakingtheparasiticeffectsdistributedinthediodeintoaccount.Basedonthepr0posedequivalentciI?uit,aKabandbalancedmixerwasdesignedandoptimized.Themeasuredconver
sionlossis
7.5 dBto 10dB from32GHzto37 GHz,whichagreedwellwiththesimulatedone?
Keywords:S chottkydiode;Kaband;bMancedmixer;electromagneticmodel;wide-bandequivalentcircuit
PACS:84.40.
基于新颖宽带肖特基二极管模型的毫米波平衡式混频器设计
牟进超,吕昕,于伟华
(北京理工大学信息与电子学院,北京100081)
摘要:介绍了一个用于混频器设计的肖特基二极管模型.根据二极管
的物理结构,建立了三维电磁模型,并采用有
限元法分析该模型.根据二极管中分布的寄生效应,建立了直到
110 GHz的宽带等效电路.基于该等效电路,设计
并优化了一个Ka频段的平衡式混频器.在32—37 GHz频率范围内,测试的变频损耗为7.5,10dB.测试结果与仿
真结果吻合地较好.
关键词:肖特基二极管;Ka波段;平衡混频器;电磁模型;宽带等效电路
中图分类号:TN454文献标识码:A
Introduc tion
Millimeterwave(MMW)andSub.Millimeterwave(SMMW)imagingsystemshavemanyadvanta.ges,suchashigherspatialresolutionwiththesamean.tennaaperturecomparedtomicrowaveimagingsystemsandthe abilitytoworkinlowvi sibilityc onditions c om—
paredtoinfraredoropticalimagingsystems.ForMMWandSMMWimagingsystems,heterodynereceiverisagoodchoice,wherethemixerisoneofthemostimpor—tantcomponents.Itcombine stheinputradiofrequency
(RF)signalandthelocaloscillating(LO)signaltoproduceanintermediatefrequency(IF)signal,whichisanonlinearproces srealizedbynonlineardevices.
AmongthenonlineardevicesinMMWand
SMMWmixers.suchassuperconductorinsulatorSll-perconductor(SIS)junctionsandhotelectronbo-lometers(HEBs)引,Schottkybarrierdiodes(SBDs)arefascinatingduetothemeritsoflowturn—onvoltageandhighresponsespeedaswellaseasyfabricationandnon.cryogenicconditionrequirement.Thustheyarewide 1vusedinmixersanddetect0rs[4.AtMMWband,theperformanceoftheSchottkydiodecannotbedescribedbytheclassicequivalentcircuitaccuratelybe c aus eatltheparasiticreactiveelements are simplyrepresentedbyatotalshuntcapacitance.Onesolution
Reeeiveddate:2010.12.03,reviseddate:2011-O 1.01收稿日
期:2010-12-03,修回日期:2011-01_O1
Foundationitem:TheNationalBasicResearchProgramofChina(201 O CB3
27505)
Biography:MOUJin-Cha0(1985.),male,Lianyungang,JiangsuProvinee,C
hina,Ph.Dstudent.Restarchfieldsincludemillimeter.waVe/Temhsemiconductordevicesandintegratedcircuits,E—mail:?
386红外与毫米波30卷istostudythehighfrequencyeffectsdistributedinthe
Schottkydiodeandbuildanequivalentcircuittakingalltheparasiticelementsintoaccount.Insteadoftes-ting,a3DEMmodelisanalyzedbyfiniteelementmethod(FEM)andawide—bandequivalentcircuitupto110GHzisbuilt.Basedontheproposedequivalentcircuit,aKa—bandbalancedmixerisdesignedandmeasured,theminimumconversionloss ofwhichis
7.5dB
1 SchottkyDiodeanditsModel
Fig.1 illustratesthephysicalstructureofthestud—ledSchottkydiodeS0130fromBeo’ ingInstituteofTech—nology.Thesemi—insulating(S.I.)GaAslayerisusedastheSBDstructureconsistsofathick,heavilydopedlayer(n+
GaAs)withathin,lightlydopedlayer(n-GaAs)on
GaAslayerleadsto itstop.Theanodeformedonthen—
Schottkycontactandthecathodepadformedonthen
+GaAslayerresultsinohmiccontact.Afingerisin—troducedtoconnecttheanodeandtheanodepad,un?derwhichi sanetchedtrenchtoreducetheparasitic
capacitancebetweenpadseffectively.Asilicondioxide(SiO2)layeronthetopofthen-GaAslayerprovidespas sivationandinsulation.Thedetailedphysicalpa-rametersoftheSchottkydiodearelistedinTable.1.Table1 PhysicalparametersofthestudiedSBD表1所研究的肖特基二极管物理参数
Fig.1 PhysicalstructureoftheSBDS 0130
图1SBDSOI30的物理结构
Thecurrent—voltage(I-V)characteristicoftheS chottkydiodesatisfiesthefollowingrelationship[],=((1)whereRistheseriesresistance;Tisthephysicaltem-peratureofthediode:ni stheidealityfactorandequalsto1 foranidealdiode;kisBoltzmanncon—stant;isthesaturationcurrent;口istheelectriccharge.AccordingtothemeasuredI-VcurveplottedinFig.2,R=20n,n=1.09,=9.8E一16A,andthereversebreakdownvoltage,=9.2V@20Aare extrac te d.
TheclassicequivalentcircuitoftheSchottkydiodeisshowninFig.3.Thedesiredmixingoccursinthenonlinearj unctionresistanceRj().TheseriesresistanceR,junctioncapacitanceC,()andshuntcapacitanceCpareparasiticelementsdegradingthe
di o d eofmetallossaswellasallresistancesbetweentheedgeofthedepletionregionandtheohmiccontact.ThejunctioncapacitanceC,()isvoltagedependentandconsistsofthecapacitanceduetothedepletionregionandthecapacitanceresultingfromthefringingfieldsaroundtheanode.TheshuntcapacitanceCrepresentsthetotalreactiveparasiticeffectsofthediodeexcludingC,,whichisinherentinallplanardiode sduetothedistributedfringingfieldsanddeterminedbythedi o d eobtainedby
Ri(v,i(v)=(2)
However,theclassicequivalentcircuitistoosim—pletoreflectalltheparasiticeffectsdistributedineach
0.0llE.3
IE一4lE.5lE6
1E.7
1E.8
1E一9l E lO
lE—l1
1E一12
】E.】 3
,r
7
,r
J
』
,
5.4—3—21O
Voltage/V
Fig.2MeasuredI-VcurveofS0130
图2S0130的测试伏安曲线
《0b0
5期MOUJin.Chaoetal:Millimeter.wavebalancedmixerbasedonanovelwide—bandSchottkydiodemodel387r一一一一一一一一一一-一_
,
ZDCp,
一iRs. :
Fig.3ClassicequivalentcircuitoftheSchottkydiode
图3肖特基二极管的经典等效电路l?
T
且
T(v)
Fig.4ImprovedequivalentcircuitoftheS c hottkydiode图4肖特基二极管的改进等效电路sectionandcannotdescribethephaseaccurately,e speciallyinMMWandSMMWb ands.whichare criti-calformixers—provedequivalentcircuitshowninFig.4isestablishedaccordingtotheelectromagneticfieldsdistributingintheSBD,takingalltheparasiticeffectsintoaccount.Cpprepresentsthefringingfieldsbetweenthepads;
T. .networkAandT..networkB s temfromthediscontinuityoftheanodepadandthecathodepadrespectively;isthecapacitanceduetothefringingfieldofthefingerandthefingerismodeledasaninductor.
Toextracttheequivalentelements,alossless3DEMmodelisbuiltaccordingtothediodestructure,as showninFig.5.Someequivalentsettingsareintroducedfor3DEMmodeling,as summarizedinTable.2.Then—layerisdividedintotwosub—layers:adielectriclayerfollowedbyaconductinglayer.Thethicknes softhedielectriclayerequalstothewidthofthe
depletionregioninthen.GaAslayer.determinedby[ere~[V6i-vkTn枷
,(3)f一
GaAs?f一whereNn一andtGaAslayerrespectively.The3D thicknessofthen—modelunderthezero—biasconditioniscalculatedusingfiniteelementmethodandtheS—parametersaregiveninFig.6.Allthereactancecomponentsincluding
Fig.53DEMmodeloftheSBDS0130
图5SBDO130的三维电磁模型canbeextractedfromtheEManalyzedresults,andtheextractedreactanceparametersarelistedinTable.3.TheS-parametersoftheequivalentcircuitexcludingandRareals oplottedinFig.6,whichagreewellwiththeEMsimulatedonesupto110GHz.
Table2EquivalentsettingsoftheSBD’ sEMmodel表2SBD电磁模型等效设置
RegionMaterialusedinHFSSaetedn-G
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