混频器基于新颖宽带肖特基二极管模型毫米波平衡式混频器设计英文

(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

山d’