射频工程师测试题.docx
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射频工程师测试题
射频工程师测试题
RFQuiz#1
1.Whatistheimpedanceoffreespace?
377ou
2.Whathappenstothenoisefigureofareceiverwhena10dBattenuatorisaddedatthe
input?
a）Noisefigureincreasesby10dB
b）Noisefiguredecreasesby10dB
c）Noisefiguredoesn'tchange
3.AnRFsystemhasalinearthroughputgainof+10dBandanoutput3rd-orderinterceptpoint
（OIP3）of+30dBm.Whatistheinput3rd-orderinterceptpoint（IIP3）?
a）+20dBm
b）+40dBm
c）+30dBm
4.Whichfiltertypehasthegreatestselectivityforagivenorder（i.e.,N=5）?
a）Bessel
b）Chebychev（ripple=0.1dB）
c）Butterworth
5.Whichmixerspuriousproductisa5th-orderproduct?
a）1*LO+5*RF
b）6*LO-1*RF
c）3*LO-2*IF
6.A2.8GHzoscillatorisphase-lockedtoa10MHzreferenceoscillatorthathasasingle-sided
phasenoiseof-100dBcat1kHzoffset.Whatisthesingle-sidedphasenoiseofthe2.8GHz
oscillatorat1kHzoffset?
a）-48.6dBc
b）-100dBc
c）-51.1dBc
7.Whatisthepowerofa2Vpk-pksinewaveacrossa50ohmload?
a）-20.0dBm
b）+10.0dBm
c）+19.0dBm
8.Which2-portS-parameteriscommonlyreferredtoas"reverseisolation"inanamplifier?
a）S21
b）S22
c）S12
9.WhataretheminimumandmaximumcombinedVSWRlimitsataninterfacecharacterizedby
a1.25:
1VSWRanda2.00:
1VSWR?
a）1.75:
1（min）,2.25:
1（max）
b）1.60:
1（min）,2.50:
1（max）
c）0.75:
1（min）,3.25:
1（max）
10.Anidealdirectionalcouplerhasadirectivityof25dBandanisolationof40dB.Whatisits
couplingvalue?
I=D+C
a）65dB
b）40dB
c）15dB
RFQuiz#21.OnaSmithchart,whatdoesapointinthebottomhalfofthechartrepresent?
a）Aninductiveimpedance
b）Acapacitiveimpedance
c）Powersaturation
2.Whilewe'reonthesubjectofSmithcharts,whatistheimpedanceofthepointatthefarleft
edgeofthecenterhorizontalline?
a）Infiniteohms（opencircuit）
b）Zeroohms（shortcircuit）
c）50ohmmatch
3.Asingle-conversiondownconverterusesahigh-sidelocaloscillator（LO）totranslatetheinput
radiofrequency（RF）toanintermediatefrequency（IF）.WillspectralinversionoccuratIF?
a）Yes,always
b）No,never
c）Sometimes
4.Whathappenstothenoisefloorofaspectrumanalyzerwhentheinputfilterresolution
bandwidthisdecreasedbytwodecades?
a）20dBincrease
b）20dBdecrease
c）40dBdecrease
5.Whatisaprimaryadvantageofaquadraturemodulator?
a）LowLOpowerrequired
b）Fourseparateoutputs
c）Single-sidebandoutput
6.WhatismeantbydBiasappliedtoantennas?
a）Isolationindecibels
b）Physicalsizerelativetointrinsicantennas
c）Gainrelativetoanisotropicradiator
7.Whatisthepowerdynamicrangeofanideal12-bitanalog-to-digitalconverter（ADC）?
a）36.12dB
b）120dB
c）72.25dB
8.Anideal10dBattenuatorisaddedinfrontofaloadthathasa2.00:
1VSWR.Whatisthe
resultingVSWRoftheload+attenuator?
a）1.07:
1
b）2.10:
1
c）12.0:
1
9.Whatisthethermalnoisepowerina1MHzbandwidthwhenthesystemtemperatureis15
degreesCelsius（assumegainandnoisefigureare0dB）?
a）-114.0dBm（ina1MHzbandwidth）
b）-114.0dBm
c）-114.0dBm/Hz
10.Twoequalamplitudetoneshaveapowerof+10dBm,andgenerateapairofequal
amplitude3rd-orderintermodulationproductsat-20dBm.Whatisthe2-tone,3rd-orderinterceptpoint（IP3）ofthesystem?
a）+40dBm
b）+25dBm
c）+20dBm
RFQuiz#3
1.Whatisaprimaryadvantagetousing90degree（quadrature）hybridcouplersinamplifier
designs?
a）Widerbandwidthpossible
b）Lownoisefigure
c）Input/outputimpedancenotdependentondevicesaslongasdeviceimpedancesareequal2.Whyisthereafrequencytermintheequationforfree-spacepathloss?
a）Thereisnofrequencyterm
b）Atmosphericabsorption
c）Antennageometryrequiresit
3.Ifanamplifierhasanoisetemperatureof60K,whatisitsnoisefigureforanambient
temperatureof290K?
a）8.0dB
b）80dB
c）0.82dB
4.Whatisaprimaryadvantageofoffset-quadrature-phase-shift-keying（OQPSK）overstandardQPSK?
a）Greaterdataratespossible
b）Greaterspectralefficiency
c）Moreconstantenvelopepower
5.Amixerhasthefollowinginputfrequencies:
RF=800MHz,LO=870MHz.Thedesiredoutputfrequencyis70MHz.Whatistheimagefrequency?
a）940MHz
b）1670MHz
c）140MHz
6.Whatisthespurious-freedynamicrangeofasystemwithIP3=+30dBmandaminimum
discerniblesignal（MDS）levelof-90dBm?
a）80dB
b）120dB
c）60dB
7.Aspectrumanalyzerdisplaysacomponentat10MHz@0dBm,30MHz@-10dBm,50MHz
@-14dBm,70MHz@-17dBm,andalloftheotheroddharmonicsuntiltheydisappearinto
thenoise.Whatwasthemostlikelyinputsignalthatcausedthespectrum?
a）A10MHzsquarewave（0Vdc）
b）A10MHztrianglewave（0Vdc）
c）A10MHzcosinewave（0Vdc）
8.OnwhichsideofarectangularwaveguideisanE-bendmade?
a）Thelongdimension
b）Theshortdimension
c）Theinside
9.Duringanetworkanalyzercalibration,whyarebothashortcircuitandanopencircuitused?
a）Theyaverageto50ohmsinanRFsystem
b）Todeterminethecharacteristicimpedanceofthemeasurementsystemc）Bothareeasytoproducetoathighaccuracy
10.Whatisthefirstharmonicof1GHz?
a）1GHz
b）2GHz
c）10GHz
RFQuiz#41.Whichofthefollowingcancausefrequencyintermodulationproductsinasystem?
a）Onlysemiconductorjunctionslikediodesandtransistors（amplifiers）b）Cableconnectors,boltedorrivetedantennapanels,isolatorsandcirculatorsc）Botha）andb）
2.Whatisthemeltingtemperatureofstandard60/40,tin/leadsolder?
a）100?
C（212?
F）
b）250?
C（482?
F）
c）186?
C（386?
F）
3.Whatisthefrequencybandforthe900MHzGSMcellularband?
a）Tx:
880-915MHz/Rx:
925-960MHz
b）Tx:
824-849MHz/Rx:
869-894MHz
c）Thereisno900MHzGSMband
4.WhatdoesGSMstandfor?
a）GeneralSystemforMobilephones
b）GreaterSpectrumforMobilephones
c）GlobalSystemforMobileCommunication
5.WhatdoesPOTSstandfor（incommunications）?
a）PlainOldTelephoneSystem
b）PersOnalTelephonySystem
c）PersonalOrbital&TerrestrialSatellite
6.Whichofthesepairsofmaterialsinthetriboelectricserieshavethegreatestchargetransferpotential?
a）Silk&Wool
b）RubberBalloon&Celluloid
c）Glass&HardRubber
7.Alongwhichsideofrectangularwaveguideisan"E"bendmade?
a）Longerside
b）Shorterside
c）"E"itherside
8.WhatisthelowestmodulationindexatwhichanFMcarrierissuppressed?
a）2.40
b）,（3.1416）
c）OnlyAMcarrierscanbesuppressed
9.Howmuchcurrentisrequiredthroughthehumanbodytocauseanonsettomuscularparalysisduringelectrocution?
a）Voltageistheculpritduringelectrocution,notcurrent
b）21mA
c）?
amp
10.Atwhatfrequencyiselectromagneticenergymaximallyabsorbedduetooxygenintheatmosphere?
a）22GHz
b）Onlywaterintheatmosphereabsorbselectromagneticenergy
c）63GHz
RFQUIZ#5
Thisquiztestsyourrecognitionoflogosfromcompanies*thatareleadersintheRFindustry.Insomecases,partofthestandardlogowascroppedbecauseithadthecompanynameincluded.Printingoutthispagetofillintheblanksisprobablythebestwaytogoaboutthispuzzle.Hoveryourcursoroveralogotoseeahintastowhattypeofproductitmanufactures.
American
____________________________Technical__Ceramics（ATC）
Piconics
____________________________,Channel__Microwave
MarkiMicrowave____________________________,ScientificAtlanta__,Anadigics
____________________________,NationalInstruments__
Remec
____________________________,AnalogDevices__,Datel
Andrew____________________________Corporation__,HittiteMicrowave____________________________,Delta__,PowerCube
Agilent____________________________Technologies__,Synergy____________________________Microwave__,PowerOne
Cypress____________________________Semiconductor__,Connecticut____________________________Microwave__,Miteq
____________________________,Vicor__,National
Semiconductor____________________________,MauryMicrowave__,Cinch
____________________________,Stanford__Microdevices
Huber+Suhner____________________________,Johanson__Dielectrics____________________________,SageLabs__,Ansoft
Atlantic____________________________Microwave__,Intusoft
Dallas____________________________Semiconductor__,Merrimac
Industries____________________________,AppliedRadio__Labs
Texas____________________________Instruments__,Trilithic
Rohde&Schwarz
Voltronics
General
Microwave,DielectricLaboratories
RFMicroDevices
GHzTechnology____________________________
__
RFQuiz#6:
WirelessCommunicationsFundamentals
1.WhichofthefollowingWLANstandardsisonadifferentfrequencybandthantheothers?
a）802.11a
b）802.11b
c）802.11g
d）802.11n
2.Whatdoestheterm"ruggedness"refertoinwirelesspoweramplifiers?
a）Abilitytowithstandthermalstress
b）Abilitytowithstandmechanicalstress
c）Abilitytowithstandloadmismatch
d）Alltheabove
3.WhichFCCregulationgovernstheunlicensedISMband?
a）Part15
b）Chapter11
c）815.00
d）Subsection11
4.InwhichsemiconductortechnologyarethemajorityofcellphonePAsmanufactured?
a）Si/SiCMOS
b）GaN
c）GaAs/InGaP
d）SiGe
5.WhatisamajoradvantageofLowTemperatureCo-firedCeramic（LTCC）substrates?
a）Denselyintegratedpassivecomponents
b）Betterthe
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