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1、Network Analyzer Basics1Network Analyzer BasicsNetwork Analysis is NOT.2Network Analyzer BasicsWhat Types of Devices are Tested?Device typeActivePassiveIntegrationHighLowAntennasSwitchesMultiplexersMixersSamplersMultipliersDiodesDuplexersDiplexersFiltersCouplersBridgesSplitters, dividersCombinersIso
2、latorsCirculatorsAttenuatorsAdaptersOpens, shorts, loadsDelay linesCablesTransmission linesWaveguideResonatorsDielectricsR, L, CsRFICsMMICsT/R modulesTransceiversReceiversTunersConvertersVCAsAmplifiersVCOsVTFsOscillatorsModulatorsVCAttensTransistors3Network Analyzer BasicsDevice Test Measurement Mod
3、elNFStimulus typeComplexSimpleComplexResponse toolSimpleDCCW Swept Swept Noise 2-toneMulti- Complex Pulsed- Protocolfreq power tone modulation RFDet/ScopeParam. An.NF Mtr.Imped. An.Power Mtr.SNAVNASAVSA84000TG/SADed. TestersI-VAbsol. PowerGain/FlatnessLCR/ZHarm. Dist.LO stabilityImage Rej.Gain/Flat.
4、Phase/GDIsolationRtn Ls/VSWRImpedanceS-parametersComprnAM-PMRFIC testFull call sequencePulsed S-parm.Pulse profilingBEREVMACPRegrowthConstell.EyeIntermodulation DistortionNFMeasurement plane4Network Analyzer BasicsLightwave Analogy to RF Energy RFIncidentReflectedTransmitted LightwaveDUT5Network Ana
5、lyzer BasicsVerify specifications of “building blocks” for more complex RF systemsEnsure distortionless transmission of communications signalslinear: constant amplitude, linear phase / constant group delaynonlinear: harmonics, intermodulation, compression, AM-to-PM conversionEnsure good match when a
6、bsorbing power (e.g., an antenna)Why Do We Need to Test Components?6Network Analyzer BasicsThe Need for Both Magnitude and Phase4. Time-domain characterization MagTime5. Vector-error correctionErrorMeasuredActual2. Complex impedance needed to design matching circuits 3. Complex values needed for dev
7、ice modeling 1. Complete characterization of linear networks High-frequency transistor model CollectorBaseEmitterS21S12S11S227Network Analyzer BasicsAgendalWhat measurements do we make?Transmission-line basicsReflection and transmission parametersS-parameter definitionlNetwork analyzer hardwareSigna
8、l separation devicesDetection typesDynamic rangeT/R versus S-parameter test setslError models and calibrationTypes of measurement errorOne- and two-port modelsError-correction choicesBasic uncertainty calculationslExample measurementslAppendix8Network Analyzer BasicsTransmission Line BasicsLow frequ
9、encieslwavelengths wire lengthlcurrent (I) travels down wires easily for efficient power transmissionlmeasured voltage and current not dependent on position along wireHigh frequencieslwavelength or length of transmission mediumlneed transmission lines for efficient power transmissionlmatching to cha
10、racteristic impedance (Zo) is very important for low reflection and maximum power transferlmeasured envelope voltage dependent on position along lineI+-9Network Analyzer BasicsTransmission line ZoZo determines relationship between voltage and current wavesZo is a function of physical dimensions and
11、r Zo is usually a real impedance (e.g. 50 or 75 ohms)characteristic impedancefor coaxial airlines (ohms)102030405060 70 80 901001.00.80.70.60.50.91.51.41.31.21.1normalized values50 ohm standardattenuation is lowest at 77 ohmspower handling capacity peaks at 30 ohms10Network Analyzer BasicsPower Tran
12、sfer EfficiencyRSRLFor complex impedances, maximum power transfer occurs when ZL = ZS* (conjugate match)Maximum power is transferred when RL = RSRL / RS00.20.40.60.811.2012345678910Load Power (normalized)11Network Analyzer BasicsTransmission Line Terminated with Zo For reflection, a transmission lin
13、e terminated in Zo behaves like an infinitely long transmission lineZs = ZoZoVrefl = 0! (all the incident power is absorbed in the load)VincZo = characteristic impedance of transmission line12Network Analyzer BasicsTransmission Line Terminated with Short, Open Zs = ZoVreflVincFor reflection, a trans
14、mission line terminated in a short or open reflects all power back to sourceIn-phase (0o) for open, out-of-phase (180o) for short13Network Analyzer BasicsTransmission Line Terminated with 25 VreflStanding wave pattern does not go to zero as with short or openZs = ZoZL = 25 Vinc14Network Analyzer Bas
15、icsHigh-Frequency Device CharacterizationTransmittedIncidentTRANSMISSIONGain / LossS-ParametersS21, S12GroupDelayTransmissionCoefficientInsertion PhaseReflectedIncidentREFLECTIONSWRS-ParametersS11, S22ReflectionCoefficientImpedance, Admittance R+jX, G+jB ReturnLoss G, T,tIncidentReflectedTransmitted
16、RBAAR=BR=15Network Analyzer BasicsReflection Parameters dBNo reflection(ZL = Zo) RLVSWR01Full reflection(ZL = open, short)0 dB1=ZL- ZOZL+OZReflection Coefficient=VreflectedVincident=FG=GReturn loss = -20 log(),Voltage Standing Wave RatioVSWR = EmaxEmin=1 + 1 - EmaxEmin16Network Analyzer BasicsSmith
17、Chart Review Smith Chart maps rectilinear impedanceplane onto polar plane0+R+jX-jXRectilinear impedance plane.-90o0o180o+-.2.4.6.81.090o 0 0Polar planeZ = ZoL= 0GConstant XConstant RSmith chartGLZ = 0=180 O1(short) Z = L=0 O1G(open) 17Network Analyzer BasicsTransmission ParametersVTransmittedVIncide
18、ntTransmission Coefficient = T=VTransmittedVIncident= tfDUTGain (dB) = 20 Log VTrans VInc = 20 log tInsertion Loss (dB) = - 20 Log VTrans VInc =- 20 log t18Network Analyzer BasicsLinear Versus Nonlinear BehaviorLinear behavior:linput and output frequencies are the same (no additional frequencies cre
19、ated)loutput frequency only undergoes magnitude and phase changeFrequencyf1TimeSin 360o * f * tFrequencyAphase shift = to * 360o * f1fDUTTimeAtoA * Sin 360o * f (t - to)InputOutputTimeNonlinear behavior:loutput frequency may undergo frequency shift (e.g. with mixers)ladditional frequencies created (
20、harmonics, intermodulation)Frequencyf119Network Analyzer BasicsCriteria for Distortionless Transmission Linear Networks Constant amplitude over bandwidth of interestMagnitudePhaseFrequencyFrequencyLinear phase over bandwidth of interest20Network Analyzer BasicsMagnitude Variation with Frequency F(t)
21、 = sin wt + 1/3 sin 3wt + 1/5 sin 5wtTimeLinear NetworkFrequencyFrequencyFrequencyMagnitudeTime21Network Analyzer BasicsPhase Variation with Frequency FrequencyMagnitudeLinear NetworkFrequencyFrequencyTime0-180-360TimeF(t) = sin wt + 1 /3 sin 3wt + 1 /5 sin 5wt22Network Analyzer BasicsDeviation from
22、 Linear Phase Use electrical delay to remove linear portion of phase responseLinear electrical length added+yieldsFrequency(Electrical delay function)FrequencyRF filter responseDeviation from linear phasePhase 1 /DivoPhase 45 /DivoFrequencyLow resolutionHigh resolution23Network Analyzer BasicsGroup
23、Delayin radiansin radians/secin degreesf in Hertz (w = 2 p f)fwfGroup Delay (t )g =-d fd w=-1360od fd f*FrequencyGroup delay rippleAverage delaytotgPhasefDfFrequencyDwwlgroup-delay ripple indicates phase distortionlaverage delay indicates electrical length of DUTlaperture of measurement is very impo
24、rtant24Network Analyzer BasicsWhy Measure Group Delay?Same p-p phase ripple can result in different group delayPhasePhaseGroup DelayGroup Delay- -d f fd w w- -d f fd w wffff25Network Analyzer BasicsCharacterizing Unknown DevicesUsing parameters (H, Y, Z, S) to characterize devices:lgives linear beha
25、vioral model of our devicelmeasure parameters (e.g. voltage and current) versus frequency under various source and load conditions (e.g. short and open circuits)lcompute device parameters from measured datalpredict circuit performance under any source and load conditionsH-parametersV1 = h11I1 + h12V
26、2I2 = h21I1 + h22V2Y-parametersI1 = y11V1 + y12V2I2 = y21V1 + y22V2Z-parametersV1 = z11I1 + z12I2V2 = z21I1 + z22I2h11 = V1I1V2=0h12 = V1V2I1=0(requires short circuit)(requires open circuit)26Network Analyzer BasicsWhy Use S-Parameters?lrelatively easy to obtain at high frequenciesnmeasure voltage t
27、raveling waves with a vector network analyzerndont need shorts/opens which can cause active devices to oscillate or self-destructlrelate to familiar measurements (gain, loss, reflection coefficient .)lcan cascade S-parameters of multiple devices to predict system performancelcan compute H, Y, or Z p
28、arameters from S-parameters if desiredlcan easily import and use S-parameter files in our electronic-simulation toolsIncidentTransmittedS21S11ReflectedS22ReflectedTransmittedIncidentb1a1b2a2S12DUTb1= S11a1+ S12a2b2= S21a1+ S22a2Port 1Port 227Network Analyzer BasicsMeasuring S-ParametersS11=Reflected
29、Incident=b1a1a2= 0S21=TransmittedIncident=b2a1a2= 0S22=ReflectedIncident=b2a2a1= 0S12=TransmittedIncident=b1a2a1= 0IncidentTransmittedS21S11Reflectedb1a1b2Z0Loada2= 0DUTForwardIncidentTransmittedS12S22Reflectedb2a2ba1= 0DUTZ0LoadReverse128Network Analyzer BasicsEquating S-Parameters with Common Meas
30、urement TermsS11 = forward reflection coefficient (input match)S22 = reverse reflection coefficient (output match)S21 = forward transmission coefficient (gain or loss)S12 = reverse transmission coefficient (isolation)Remember, S-parameters are inherently complex, linear quantities - however, we ofte
31、n express them in a log-magnitude format29Network Analyzer Basics FrequencyFrequencyTimeTimeCriteria for Distortionless Transmission Nonlinear NetworksSaturation, crossover, intermodulation, and other nonlinear effects can cause signal distortionEffect on system depends on amount and type of distort
32、ion and system architecture30Network Analyzer BasicsMeasuring Nonlinear BehaviorMost common measurements:lusing a network analyzer and power sweepsgain compressionAM to PM conversionlusing a spectrum analyzer + source(s)harmonics, particularly second and thirdintermodulation products resulting from
33、two or more RF carriersRL 0 dBm ATTEN 10 dB 10 dB / DIVCENTER 20.00000 MHz SPAN 10.00 kHzRB 30 Hz VB 30 Hz ST 20 sec LPF8563ASPECTRUM ANALYZER 9 kHz - 26.5 GHzLPFDUT31Network Analyzer BasicsWhat is the Difference Between Network and Spectrum Analyzers?.Amplitude RatioFrequency AmplitudeFrequency8563
34、ASPECTRUM ANALYZER 9 kHz - 26.5 GHzMeasures known signalMeasures unknown signals Network analyzers:lmeasure components, devices, circuits, sub-assemblieslcontain source and receiverldisplay ratioed amplitude and phase(frequency or power sweeps)loffer advanced error correction Spectrum analyzers:lmea
35、sure signal amplitude characteristicscarrier level, sidebands, harmonics.)lcan demodulate (& measure) complex signalslare receivers only (single channel)lcan be used for scalar component test (nophase) with tracking gen. or ext. source(s)32Network Analyzer BasicsAgendalWhat measurements do we make?l
36、Network analyzer hardwarelError models and calibrationlExample measurementslAppendix33Network Analyzer BasicsGeneralized Network Analyzer Block DiagramRECEIVER / DETECTORPROCESSOR / DISPLAYREFLECTED(A)TRANSMITTED(B)INCIDENT (R)SIGNALSEPARATIONSOURCEIncidentReflectedTransmittedDUT34Network Analyzer B
37、asicsSourcelSupplies stimulus for systemlSwept frequency or powerlTraditionally NAs used separate sourcelMost Agilent analyzers sold today have integrated, synthesized sources35Network Analyzer BasicsSignal SeparationTest PortDetectordirectional couplersplitterbridgemeasure incident signal for refer
38、enceseparate incident and reflected signalsRECEIVER / DETECTORPROCESSOR / DISPLAYREFLECTED(A)TRANSMITTED(B)INCIDENT (R)SIGNALSEPARATIONSOURCEIncidentReflectedTransmittedDUT36Network Analyzer BasicsDirectivityDirectivity is a measure of how well a coupler can separate signals moving in opposite direc
39、tionsTest port(undesired leakage signal)(desired reflected signal)Directional Coupler37Network Analyzer BasicsInteraction of Directivity with the DUT (Without Error Correction)Data MaxAdd in-phaseDeviceDirectivityReturn LossFrequency03060DUT RL = 40 dBAdd out-of-phase (cancellation)DeviceDirectivity
40、Data = Vector SumDirectivityDeviceData Min38Network Analyzer BasicsDetector TypesTuned ReceiverScalar broadband (no phase information)Vector(magnitude and phase)DiodeDCACRFIF FilterIF = F LOFRFRFLOADC / DSPRECEIVER / DETECTORPROCESSOR / DISPLAYREFLECTED(A)TRANSMITTED(B)INCIDENT (R)SIGNALSEPARATIONSO
41、URCEIncidentReflectedTransmittedDUT39Network Analyzer BasicsBroadband Diode DetectionlEasy to make broadbandlInexpensive compared to tuned receiverlGood for measuring frequency-translating deviceslImprove dynamic range by increasing powerlMedium sensitivity / dynamic range10 MHz26.5 GHz40Network Ana
42、lyzer BasicsNarrowband Detection - Tuned ReceiverlBest sensitivity / dynamic rangelProvides harmonic / spurious signal rejectionlImprove dynamic range by increasing power, decreasing IF bandwidth, or averaginglTrade off noise floor and measurement speed10 MHz26.5 GHzADC / DSP41Network Analyzer Basic
43、sComparison of Receiver Techniques -100 dBm Sensitivity 0 dB-50 dB-100 dB0 dB-50 dB-100 dB-60 dBm Sensitivity Broadband (diode) detectionNarrowband (tuned-receiver) detectionlhigher noise floorlfalse responseslhigh dynamic rangelharmonic immunityDynamic range = maximum receiver power - receiver nois
44、e floor42Network Analyzer BasicsDynamic Range and AccuracyDynamic range is very important for measurement accuracy!phase errormagn error+-43Network Analyzer BasicsT/R Versus S-Parameter Test SetslRF always comes out port 1lport 2 is always receiverlresponse, one-port cal availablelRF comes out port
45、1 or port 2lforward and reverse measurementsltwo-port calibration possibleTransmission/Reflection Test SetPort 1Port 2SourceBRADUTFwdPort 1Port 2Transfer switchSourceBRAS-Parameter Test SetDUTFwdRev44Network Analyzer BasicsRECEIVER / DETECTORPROCESSOR / DISPLAYREFLECTED(A)TRANSMITTED(B)INCIDENT (R)S
46、IGNALSEPARATIONSOURCEIncidentReflectedTransmittedDUTProcessor / Displaylmarkersllimit lineslpass/fail indicatorsllinear/log formatslgrid/polar/Smith chartsACTIVE CHANNELRESPONSESTIMULUSENTRYINSTRUMENT STATE R CHANNELR LTSHP-IB STATUSNETWORK ANYZER50MH-20GHzPORT 2PORT 145Network Analyzer BasicsIntern
47、al Measurement AutomationSimple: recall statesMore powerful:lTest sequencingnavailable on 8753/ 8720 familiesnkeystroke recordingnsome advanced functionslIBASICnavailable on 8712 familynsophisticated programsncustom user interfacesABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789 + - / * = ( ) & , . / ? ; : 1 AS
48、SIGN Hp8714 TO 800 2 OUTPUT Hp8714;SYST:PRES; *WAI 3 OUTPUT Hp8714;ABOR;:INIT1:CONT OFF;*WAI 4 OUTPUT Hp8714;DISP:ANN:FREQ1:MODE SSTOP 5 OUTPUT Hp8714;DISP:ANN:FREQ1:MODE CSPAN 6 OUTPUT Hp8714;SENS1:FREQ:CENT 175000000 HZ;*WAI 7 OUTPUT Hp8714;ABOR;:INIT1:CONT OFF;:INIT1;*WAI 8 OUTPUT Hp8714;DISP:WIN
49、D1:TRAC:Y:AUTO ONCE 9 OUTPUT Hp8714;CALC1:MARK1 ON 10 OUTPUT Hp8714;CALC1:MARK:FUNC BWID 11 OUTPUT Hp8714;SENS2:STAT ON; *WAI 12 OUTPUT Hp8714;SENS2:FUNC XFR:POW:RAT 1,0;DET NBAN; *WAI 13 OUTPUT Hp8714;ABOR;:INIT1:CONT OFF;:INIT1;*WAI 14 OUTPUT Hp8714;DISP:WIND2:TRAC:Y:AUTO ONCE 15 OUTPUT Hp8714;ABO
50、R;:INIT1:CONT ON;*WAI 16 END46Network Analyzer BasicsAgilents Series of HF Vector AnalyzersMicrowaveRF8510C seriesl110 GHz in coaxlhighest accuracylmodular, flexiblelpulse systemslTx/Rx module test8720ET/ES seriesl13.5, 20, 40 GHzleconomicallfast, small, integratedltest mixers, high-power amps8712ET
51、/ES seriesl1.3, 3 GHzllow costlnarrowband and broadband detectionlIBASIC / LAN8753ET/ES seriesl3, 6 GHzlhighest RF accuracylflexible hardwarelmore features lOffset and harmonic RF sweeps47Network Analyzer BasicsAgilents LF/RF Vector AnalyzersE5100A/Bl180, 300 MHzleconomicallfast, smallltarget market
52、s: crystals, resonators, filterslequivalent-circuit modelslevaporation-monitor-function option4395A/4396Bl500 MHz (4395A), 1.8 GHz (4396B)limpedance-measuring optionlfast, FFT-based spectrum analysisltime-gated spectrum-analyzer optionlIBASIClstandard test fixturesLFCombination NA / SA48Network Anal
53、yzer BasicsSpectrum Analyzer / Tracking GeneratorTracking generatorRF inTG outf = IFSpectrum analyzerIFLODUTKey differences from network analyzer:lone channel - no ratioed or phase measurementslMore expensive than scalar NA (but better dynamic range)lOnly error correction available is normalization
54、(and possibly open-short averaging)lPoorer accuracylSmall incremental cost if SA is required for other measurements8563ASPECTRUM ANALYZER 9 kHz - 26.5 GHzDUT49Network Analyzer BasicsAgendaWhy do we even need error-correction and calibration?l It is impossible to make perfect hardwarel It would be ex
55、tremely expensive to make hardware good enough to eliminate the need for error correctionlWhat measurements do we make?lNetwork analyzer hardwarelError models and calibrationlExample measurementslAppendix50Network Analyzer BasicsCalibration TopicslWhat measurements do we make?lNetwork analyzer hardw
56、arelError models and calibrationlmeasurement errorslwhat is vector error correction?lcalibration typeslaccuracy exampleslcalibration considerationslExample measurementslAppendix51Network Analyzer BasicsSystematic errorsldue to imperfections in the analyzer and test setuplassumed to be time invariant
57、 (predictable)Random errorslvary with time in random fashion (unpredictable)lmain contributors: instrument noise, switch and connector repeatabilityDrift errorsldue to system performance changing after a calibration has been donelprimarily caused by temperature variationMeasurement Error ModelingMea
58、sured DataUnknown DeviceSYSTEMATICRANDOMDRIFTErrors:CALRE-CAL52Network Analyzer BasicsSystematic Measurement ErrorsABSourceMismatchLoadMismatchCrosstalkDirectivityDUTFrequency responselreflection tracking (A/R)ltransmission tracking (B/R)RSix forward and six reverse error terms yields 12 error terms
59、 for two-port devices53Network Analyzer BasicsTypes of Error Correctionlresponse (normalization)nsimple to performnonly corrects for tracking errorsnstores reference trace in memory,then does data divided by memorylvectornrequires more standardsnrequires an analyzer that can measure phasenaccounts f
60、or all major sources of systematic errorS11mS11aSHORTOPENLOADthruthru54Network Analyzer BasicsWhat is Vector-Error Correction?lProcess of characterizing systematic error termsnmeasure known standardsnremove effects from subsequent measurementsl1-port calibration (reflection measurements)nonly 3 syst
61、ematic error terms measuredndirectivity, source match, and reflection trackinglFull 2-port calibration (reflection and transmission measurements)n12 systematic error terms measurednusually requires 12 measurements on four known standards (SOLT)lStandards defined in cal kit definition filennetwork an
62、alyzer contains standard cal kit definitionsnCAL KIT DEFINITION MUST MATCH ACTUAL CAL KIT USED!nUser-built standards must be characterized and entered into user cal-kit55Network Analyzer BasicsReflection: One-Port ModelED = DirectivityERT = Reflection trackingES = Source MatchS11M = MeasuredS11A = A
63、ctualTo solve for error terms, we measure 3 standards to generate 3 equations and 3 unknownsS11MS11AESERTED1RF inError AdapterS11MS11ARF inIdeallAssumes good termination at port two if testing two-port deviceslIf using port 2 of NA and DUT reverse isolation is low (e.g., filter passband):n assumptio
64、n of good termination is not valid n two-port error correction yields better resultsS11M = ED + ERT1 - ES S11AS11A56Network Analyzer BasicsBefore and After One-Port Calibrationdata before 1-port calibrationdata after 1-port calibration02040606000120002.0Return Loss (dB)VSWR1.11.011.001MHz57Network A
65、nalyzer BasicsTwo-Port Error CorrectionlEach actual S-parameter is a function of all four measured S-parameterslAnalyzer must make forward and reverse sweep to update any one S-parameterlLuckily, you dont need to know these equations to use network analyzers!Port 1Port 2ES11S21S12S22ESEDERTETTELa1b1
66、AAAAXa2b2Forward model=fwd directivity=fwd source match=fwd reflection tracking=fwd load match=fwd transmission tracking=fwd isolationESEDERTETTELEX=rev reflection tracking=rev transmission tracking=rev directivity=rev source match=rev load match=rev isolationESEDERTETTELEXPort 1Port 2S11SS12S22ESED
67、ERTETTELa1b1AAAEX21Aa2b2Reverse model58Network Analyzer BasicsCrosstalk: Signal Leakage Between Test Ports During TransmissionlCan be a problem with:nhigh-isolation devices (e.g., switch in open position)nhigh-dynamic range devices (some filter stopbands)lIsolation calibrationnadds noise to error mo
68、del (measuring near noise floor of system)nonly perform if really needed (use averaging if necessary)nif crosstalk is independent of DUT match, use two terminationsnif dependent on DUT match, use DUT with termination on outputDUTDUTLOADDUTLOAD59Network Analyzer BasicsErrors and Calibration Standards
69、 lConvenientlGenerally not accuratelNo errors removedlEasy to performlUse when highest accuracy is not requiredlRemoves frequency response errorlFor reflection measurementslNeed good termination for high accuracy with two-port deviceslRemoves these errors: Directivity Source match Reflection trackin
70、g lHighest accuracylRemoves these errors: Directivity Source, load match Reflection tracking Transmission tracking Crosstalk UNCORRECTED RESPONSE 1-PORT FULL 2-PORTDUTDUTDUTDUTthruthruENHANCED-RESPONSElCombines response and 1-portlCorrects source match for transmission measurementsSHORTOPENLOADSHORT
71、OPENLOADSHORTOPENLOAD60Network Analyzer Basicsl Transmission Trackingl Crosstalkl Source matchl Load matchS-parameter (two-port) T/R (response, isolation)TransmissionTest Set (cal type)*( )Calibration Summaryl Reflection trackingl Directivityl Source matchl Load matchS-parameter (two-port) T/R (one-
72、port)ReflectionTest Set (cal type)error cannot be corrected*enhanced response cal corrects for source match during transmission measurementserror can be correctedSHORTOPENLOAD61Network Analyzer BasicsReflection Example Using a One-Port CalDUT16 dB RL (.158)1 dB loss (.891)Load match:18 dB (.126).158
73、(.891)(.126)(.891) = .100Directivity:40 dB (.010)Measurement uncertainty: -20 * log (.158 + .100 + .010) = 11.4 dB (-4.6dB) -20 * log (.158 - .100 - .010) = 26.4 dB (+10.4 dB)Remember: convert all dB values to linear for uncertainty calculations! or loss(linear) = 10( )-dB 20 62Network Analyzer Basi
74、csUsing a One-Port Cal + AttenuatorLow-loss bi-directional devicesgenerally require two-port calibration for low measurement uncertaintyLoad match:18 dB (.126)DUT16 dB RL (.158)1 dB loss (.891)10 dB attenuator (.316) SWR = 1.05 (.024).158 (.891)(.316)(.126)(.316)(.891) = .010(.891)(.024)(.891) = .01
75、9Directivity:40 dB (.010) Worst-case error = .010 + .010 + .019 = .039Measurement uncertainty: -20 * log (.158 + .039) = 14.1 dB (-1.9 dB) -20 * log (.158 - .039) = 18.5 dB (+2.5 dB)63Network Analyzer BasicsTransmission Example Using Response CalRL = 14 dB (.200)RL = 18 dB (.126)Thru calibration (no
76、rmalization) builds error into measurement due to source and load match interactionCalibration Uncertainty = (1 S L) = (1 (.200)(.126) = 0.22 dB64Network Analyzer BasicsFilter Measurement with Response CalSource match = 14 dB (.200)1(.126)(.158) = .020(.158)(.200) = .032(.126)(.891)(.200)(.891) = .0
77、20Measurement uncertainty = 1 (.020+.020+.032) = 1 .072 = + 0.60 dB - 0.65 dB DUT1 dB loss (.891)16 dB RL (.158)Total measurement uncertainty: +0.60 + 0.22 = + 0.82 dB -0.65 - 0.22 = - 0.87 dBLoad match = 18 dB (.126)65Network Analyzer BasicsMeasuring Amplifiers with a Response CalTotal measurement
78、uncertainty: +0.44 + 0.22 = + 0.66 dB -0.46 - 0.22 = - 0.68 dBMeasurement uncertainty = 1 (.020+.032) = 1 .052 = + 0.44 dB - 0.46 dB1(.126)(.158) = .020 DUT16 dB RL (.158)(.158)(.200) = .032Source match = 14 dB (.200)Load match = 18 dB (.126)66Network Analyzer BasicsFilter Measurements using the Enh
79、anced Response CalibrationMeasurement uncertainty = 1 (.020+.0018+.0028) = 1 .0246 = + 0.211 dB - 0.216 dBTotal measurement uncertainty: 0.22 + .02 = 0.24 dBCalibration Uncertainty = Effective source match = 35 dB!Source match = 35 dB (.0178)1(.126)(.158) = .020(.126)(.891)(.0178)(.891) = .0018 DUT1
80、 dB loss (.891)16 dB RL (.158)Load match = 18 dB (.126)(.158)(.0178) = .0028(1(1 S L) = (1 (.0178)(.126) = .02 dB67Network Analyzer BasicsUsing the Enhanced Response Calibration Plus an AttenuatorMeasurement uncertainty = 1 (.006+.0005+.0028) = 1 .0093 = 0.08 dBTotal measurement uncertainty: 0.01 +
81、.08 = 0.09 dBSource match = 35 dB (.0178)1(.0366)(.158) = .006(.0366)(.891)(.0178)(.891) = .0005 DUT1 dB loss (.891)16 dB RL (.158)Effective load match = (.316)(.316)(.126) + .024 = .0366 (28.7dB)(.158)(.0178) = .002810 dB attenuator (.316) SWR = 1.05 (.024 linear or 32.4 dB)Analyzer load match =18
82、dB (.126)Calibration Uncertainty = = (1 (.0178)(.0366) = .01 dB(1(1 S L)68Network Analyzer BasicsCalculating Measurement Uncertainty After a Two-Port CalibrationCorrected error terms:(8753ES 1.3-3 GHz Type-N)Directivity=47 dBSource match =36 dBLoad match= 47 dBRefl. tracking = .019 dB Trans. trackin
83、g =.026 dBIsolation=100 dB DUT1 dB loss (.891)16 dB RL (.158)Transmission uncertainty= 0.891 .0056 = 1 dB 0.05 dB (worst-case)Reflection uncertainty= 0.158 .0088 = 16 dB +0.53 dB, -0.44 dB (worst-case)69Network Analyzer BasicsResponse versus Two-Port CalibrationCH1 S21&Mlog MAG1 dB/REF 0 dB CorCH2 M
84、EMlog MAGREF 0 dB1 dB/ CorUncorrectedAfter two-port calibrationSTART 2 000.000 MHzSTOP 6 000.000 MHzx212After response calibrationMeasuring filter insertion loss70Network Analyzer BasicsVariety of modules cover 30 kHz to 26.5 GHzSix connector types available (50 and 75 )Single-connectionnreduces cal
85、ibration timenmakes calibrations easy to performnminimizes wear on cables and standardsneliminates operator errorsHighly repeatable temperature-compensated terminations provide excellent accuracyECal: Electronic Calibration (85060/90 series)8509385093A Electronic Calibration Module30 kHz - 6 GHzsaMi
86、crowave modules use a transmission line shunted by PIN-diode switches in various combinations71Network Analyzer BasicsAdapter ConsiderationsTerminationAdapterDUT Coupler directivity = 40 dBleakage signaldesired signalreflection from adapterAPC-7 calibration done hereDUT has SMA (f) connectors= measu
87、red r r+adapterr rDUTr rDirectivity +Worst-caseSystem Directivity28 dB17 dB14 dBAPC-7 to SMA (m)SWR:1.06APC-7 to N (f) + N (m) to SMA (m)SWR:1.05 SWR:1.25APC-7 to N (m) + N (f) to SMA (f) + SMA (m) to (m)SWR:1.05 SWR:1.25 SWR:1.15Adapting from APC-7 to SMA (m)72Network Analyzer BasicsCalibrating Non
88、-Insertable DevicesWhen doing a through cal, normally test ports mate directlylcables can be connected directly without an adapterlresult is a zero-length through What is an insertable device?lhas same type of connector, but different sex on each portlhas same type of sexless connector on each port
89、(e.g. APC-7)What is a non-insertable device?lone that cannot be inserted in place of a zero-length throughlhas same connectors on each port (type and sex)lhas different type of connector on each port (e.g., waveguide on one port, coaxial on the other)What calibration choices do I have for non-insert
90、able devices?luse an uncharacterized through adapterluse a characterized through adapter (modify cal-kit definition)lswap equal adaptersladapter removalDUT73Network Analyzer BasicsSwap Equal Adapters MethodDUTPort 1Port 21. Transmission cal using adapter A.2. Reflection cal using adapter B.3. Measur
91、e DUT using adapter B.Port 1Port 2Adapter AAdapter BPort 1Port 2Adapter BPort 1Port 2DUTAccuracy depends on how well the adapters are matched - loss, electrical length, match and impedance should all be equal74Network Analyzer BasicsAdapter Removal CalibrationlCalibration is very accurate and tracea
92、blelIn firmware of 8753, 8720 and 8510 serieslAlso accomplished with ECal modules (85060/90)lUses adapter with same connectors as DUTlMust specify electrical length of adapter to within 1/4 wavelength of highest frequency (to avoid phase ambiguity)DUTPort 1Port 21. Perform 2-port cal with adapter on
93、 port 2. Save in cal set 1.2. Perform 2-port cal with adapter on port 1. Save in cal set 2.4. Measure DUT without cal adapter.3. Use ADAPTER REMOVAL to generate new cal set.CAL MORE MODIFY CAL SETADAPTER REMOVALCal Set 1Port 1Port 2Adapter BCal AdapterCal AdapterCal Set 2Port 1Port 2Adapter BPort 2A
94、dapter BDUTPort 175Network Analyzer BasicsThru-Reflect-Line (TRL) CalibrationWe know about Short-Open-Load-Thru (SOLT) calibration.What is TRL?lA two-port calibration techniquelGood for noncoaxial environments (waveguide, fixtures, wafer probing)lUses the same 12-term error model as the more common
95、SOLT callUses practical calibration standards that are easily fabricated and characterized lTwo variations: TRL (requires 4 receivers) and TRL* (only three receivers needed)lOther variations: Line-Reflect-Match (LRM), Thru-Reflect-Match (TRM), plus many others TRL was developed for non-coaxial micro
96、wave measurements76Network Analyzer BasicsAgendalWhat measurements do we make?lNetwork analyzer hardwarelError models and calibrationlExample measurementslAppendix77Network Analyzer BasicsFrequency Sweep - Filter TestCH1 S11log MAG5dB/REF 0 dBCENTER 200.000 MHzSPAN 50.000 MHzReturn losslog MAG10dB/R
97、EF 0 dBCH1 S21 START .300 000 MHzSTOP 400.000 000 MHz Cor 69.1dB Stopband rejectionInsertion lossSCH1 21log MAG1dB/REF 0 dB Cor Cor START 2 000.000 MHzSTOP 6 000.000 MHzx212m1: 4.000 000 GHz -0.16 dBm2-ref: 2.145 234 GHz 0.00 dB1ref278Network Analyzer BasicsSegment 3: 29 ms (108 points, -10 dBm, 600
98、0 Hz)Optimize Filter Measurements with Swept-List Mode CH1 S21 log MAG12 dB/REF 0 dB START 525.000 000 MHzPRm PASSSTOP 1 275.000 000 MHzSegment 1: 87 ms (25 points, +10 dBm, 300 Hz)Segments 2,4: 52 ms (15 points, +10 dBm, 300 Hz)Segment 5: 129 ms (38 points, +10 dBm, 300 Hz)Linear sweep: 676 ms(201
99、pts, 300 Hz, -10 dBm)Swept-list sweep: 349 ms(201 pts, variable BWs & power)79Network Analyzer BasicsPower Sweeps - CompressionSaturated output powerOutput Power (dBm)Input Power (dBm)Compression regionLinear region (slope = small-signal gain)80Network Analyzer BasicsCH1 S21 1og MAG 1 dB/ REF 32 dB
100、30.991 dB 12.3 dBmPower Sweep - Gain Compression0START -10 dBm CW 902.7 MHz STOP 15 dBm11 dB compression: input power resulting in 1 dB drop in gain81Network Analyzer BasicsAM to PM ConversionAM - PM Conversion =Mag(Pmout)Mag(Amin)(deg/dB)DUTAmplitudeTimeAM (dB)PM (deg)Mag(AMout)Mag(Pmout)Output Res
101、ponseAmplitudeTimeAM (dB)PM (deg)Mag(Amin)Test StimulusPower sweepIQAM to PM conversion can cause bit errorsMeasure of phase deviation caused by amplitude variationslAM can be undesired: supply ripple, fading, thermallAM can be desired:modulation (e.g. QAM)82Network Analyzer BasicsMeasuring AM to PM
102、 Conversion lUse transmission setup with a power sweeplDisplay phase of S21lAM - PM = 0.86 deg/dB Stop 0.00 dBmRef 21.50 dB Stop 0.00 dBm1:TransmissionLog Mag 1.0 dB/Start -10.00 dBmCW 900.000 MHzStart -10.00 dBmCW 900.000 MHz2:Transmission /MPhase 5.0 deg/ Ref -115.7 deg 12112 Ch1:Mkr1 -4.50 dBm 20
103、.48 dB Ch2:Mkr2 1.00 dB 0.86 deg83Network Analyzer BasicsAgendalWhat measurements do we make?lNetwork analyzer hardwarelError models and calibrationlExample measurementslAppendixlAdvanced Topicstime domain frequency-translating deviceshigh-power amplifiersextended dynamic rangemultiport devicesin-fi
104、xture measurementscrystal resonatorsbalanced/differentiallInside the network analyzerlChallenge quiz!84Network Analyzer BasicsTime-Domain Reflectometry (TDR)lWhat is TDR?ntime-domain reflectometrynanalyze impedance versus timendistinguish between inductive and capacitive transitionslWith gating:nana
105、lyze transitionsnanalyzer standardsZotimeimpedancenon-Zo transmission lineinductive transitioncapacitive transition85Network Analyzer Basicslstart with broadband frequency sweep (often requires microwave VNA)luse inverse-Fourier transform to compute time-domainlresolution inversely proportionate to
106、frequency spanCH1 S22 Re50 mU/REF 0 UCH1 START 0 sSTOP 1.5 ns Cor 20 GHz6 GHzTime DomainFrequency Domaintf 1/s*F(s) F(t)*dt0tIntegrateftfTDRF-1TDR Basics Using a Network AnalyzerF-186Network Analyzer BasicsTime-Domain GatinglTDR and gating can remove undesired reflections (a form of error correction
107、)lOnly useful for broadband devices (a load or thru for example)lDefine gate to only include DUTlUse two-port calibrationCH1 MEM Re20 mU/REF 0 UCH1 START 0 sSTOP 1.5 ns CorPRmRISE TIME 29.994 ps 8.992 mm 1231: 48.729 mU 638 ps 2: 24.961 mU 668 ps 3: -10.891 mU 721 ps Thru in time domainCH1 S11&M log
108、 MAG5 dB/REF 0 dB START .050 000 000 GHzSTOP 20.050 000 000 GHz GateCorPRm 122: -15.78 dB 6.000 GHz 1: -45.113 dB 0.947 GHz Thru in frequency domain, with and without gating87Network Analyzer BasicsTen Steps for Performing TDR1. Set up desired frequency range (need wide span for good spatial resolut
109、ion)2. Under SYSTEM, transform menu, press set freq low pass3. Perform one- or two-port calibration4. Select S11 measurement *5. Turn on transform (low pass step) *6. Set format to real *7. Adjust transform window to trade off rise time with ringing and overshoot *8. Adjust start and stop times if d
110、esired9. For gating:lset start and stop frequencies for gatelturn gating on *ladjust gate shape to trade off resolution with ripple *10. To display gated response in frequency domainlturn transform off (leave gating on) *lchange format to log-magnitude * If using two channels (even if coupled), thes
111、e parameters must be set independently for second channel88Network Analyzer BasicsTime-Domain TransmissionCH1 S21 log MAG15 dB/ REF 0 dBSTART -1 usSTOP 6 usCor RF LeakageSurfaceWaveTripleTravelRF OutputRF InputTriple TravelMain WaveLeakage CH1 S21log MAG10 dB/ REF 0 dBCorGate onGate off89Network Ana
112、lyzer BasicsTime-Domain Filter TuningDeterministic method used for tuning cavity-resonator filtersTraditional frequency-domain tuning is very difficult:nlots of training needednmay take 20 to 90 minutes to tune a single filterNeed VNA with fast sweep speeds and fast time-domain processing90Network A
113、nalyzer BasicsFilter Reflection in Time DomainSet analyzers center frequency = center frequency of the filterMeasure S11 or S22 in the time domainNulls in the time-domain response correspond to individual resonators in filter91Network Analyzer BasicsTuning Resonator #3Easier to identify mistuned res
114、onator in time-domain: null #3 is missingHard to tell which resonator is mistuned from frequency-domain responseAdjust resonators by minimizing nullAdjust coupling apertures using the peaks in-between the dips 92Network Analyzer BasicsFrequency-Translating DevicesMedium-dynamic range measurements (3
115、5 dB)High-dynamic range measurements (100 dB)FilterReference mixerRef out Ref in AttenuatorAttenuatorPower splitterESG-D4000ADUTAttenuator8753ES FilterAttenuatorAttenuatorRef InStart: 900 MHzStop: 650 MHzStart: 100 MHzStop: 350 MHzFixed LO: 1 GHzLO power: 13 dBmFREQ OFFSON offLOMENUDOWNCONVERTERUPCO
116、NVERTERRF LORF 2END32.008 MHz32.058 MHz2002000 dBm0 dBm200Hz200HzSEG START STOP POINTS POWER IFBW32.052 MHzCh1CorZ: R phase 40 / REF 0 1: 15.621 USTART 31.995 MHzSTOP 32.058 MHz31.998 984 925 MHzMin1Example of crystal resonator measurement100Network Analyzer BasicsBalanced-Device MeasurementsATN-400
117、0 series (4-port test set + software)measure tough singled-ended devices like couplersmeasure fully-balanced or single-ended-to-balanced DUTscharacterize mode conversions (e.g. common-to-differential)incorporates 4-port error correction for exceptional accuracyworks with 8753ES and 8720ES analyzersm
118、ore info at Channel Partnersa101Network Analyzer BasicsTraditional Scalar AnalyzerExample: 8757D/Elrequires external detectors, couplers, bridges, splitterslgood for low-cost microwave scalar applications DetectorDUTBridgeTerminationReflectionTransmissionDetectorDetectorRFRABRFRABDUTprocessor/displa
119、ysourceRECEIVER / DETECTORPROCESSOR / DISPLAYREFLECTED(A)TRANSMITTED(B)INCIDENT (R)SIGNALSEPARATIONSOURCEIncidentReflectedTransmittedDUT102Network Analyzer BasicsDirectivity =Coupling Factor (fwd) x Loss (through arm)Isolation (rev)Directivity (dB) = Isolation (dB) - Coupling Factor (dB) - Loss (dB)
120、Directional Coupler Directivity Directivity = 50 dB - 30 dB - 10 dB = 10 dBDirectivity = 60 dB - 20 dB - 10 dB = 30 dB10 dB30 dB50 dB10 dB20 dB60 dBDirectivity = 50 dB - 20 dB = 30 dB20 dB50 dBTest portExamples:Test portTest port103Network Analyzer BasicsOne Method of Measuring Coupler Directivity A
121、ssume perfect load (no reflection)short1.0 (0 dB) (reference)Coupler Directivity35 dB (.018)Sourceload.018 (35 dB) (normalized)SourceDirectivity = 35 dB - 0 dB= 35 dB104Network Analyzer BasicsDirectional BridgeTest PortDetector50 50 50 l50-ohm load at test port balances the bridge - detector reads z
122、erolNon-50-ohm load imbalances bridgelMeasuring magnitude and phase of imbalance gives complex impedancelDirectivity is difference between maximum and minimum balance105Network Analyzer BasicsRECEIVER / DETECTORPROCESSOR / DISPLAYREFLECTED(A)TRANSMITTED(B)INCIDENT (R)SIGNALSEPARATIONSOURCEIncidentRe
123、flectedTransmittedDUTNA Hardware: Front Ends, Mixers Versus SamplersIt is cheaper and easier to make broadband front ends using samplers instead of mixersMixer-based front endADC / DSPSampler-based front end SHarmonic generatorffrequency combADC / DSP106Network Analyzer BasicsThree Versus Four-Recei
124、ver AnalyzersPort 1Transfer switchPort 2SourceBR1AR2Port 1Port 2Transfer switchSourceBRA3 receiverslmore economicallTRL*, LRM* cals onlylincludes:n8753ESn8720ES (standard)4 receiverslmore expensiveltrue TRL, LRM calslincludes:n8720ES (option 400)n8510C107Network Analyzer BasicsWhy Are Four Receivers
125、 Better Than Three?TRLTRL*8720ES Option 400 adds fourth sampler, allowing full TRL calibrationlTRL*nassumes the source and load match of a test port are equal(port symmetry between forward and reverse measurements)nthis is only a fair assumption for three-receiver network analyzerslTRLnfour receiver
126、s are necessary to make the required measurements nTRL and TRL* use identical calibration standardslIn noncoaxial applications, TRL achieves better source and load match correction than TRL*lWhat about coaxial applications?nSOLT is usually the preferred calibration methodncoaxial TRL can be more acc
127、urate than SOLT, but not commonly used108Network Analyzer BasicsChallenge Quiz1. Can filters cause distortion in communications systems?A. Yes, due to impairment of phase and magnitude responseB. Yes, due to nonlinear components such as ferrite inductorsC. No, only active devices can cause distortio
128、nD. No, filters only cause linear phase shiftsE. Both A and B above2. Which statement about transmission lines is false?A. Useful for efficient transmission of RF powerB. Requires termination in characteristic impedance for low VSWRC. Envelope voltage of RF signal is independent of position along li
129、neD. Used when wavelength of signal is small compared to length of lineE. Can be realized in a variety of forms such as coaxial, waveguide, microstrip3. Which statement about narrowband detection is false?A. Is generally the cheapest way to detect microwave signalsB. Provides much greater dynamic ra
130、nge than diode detectionC. Uses variable-bandwidth IF filters to set analyzer noise floorD. Provides rejection of harmonic and spurious signalsE. Uses mixers or samplers as downconverters109Network Analyzer BasicsChallenge Quiz (continued)4. Maximum dynamic range with narrowband detection is defined
131、 as:A. Maximum receiver input power minus the stopband of the device under testB. Maximum receiver input power minus the receivers noise floorC. Detector 1-dB-compression point minus the harmonic level of the sourceD. Receiver damage level plus the maximum source output powerE. Maximum source output
132、 power minus the receivers noise floor5. With a T/R analyzer, the following error terms can be corrected:A. Source match, load match, transmission trackingB. Load match, reflection tracking, transmission trackingC. Source match, reflection tracking, transmission trackingD. Directivity, source match,
133、 load matchE. Directivity, reflection tracking, load match6. Calibration(s) can remove which of the following types of measurement error?A. Systematic and driftB. Systematic and randomC. Random and driftD. Repeatability and systematicE. Repeatability and drift110Network Analyzer BasicsChallenge Quiz
134、 (continued)7. Which statement about TRL calibration is false?A. Is a type of two-port error correctionB. Uses easily fabricated and characterized standardsC. Most commonly used in noncoaxial environmentsD. Is not available on the 8720ES family of microwave network analyzersE. Has a special version
135、for three-sampler network analyzers8. For which component is it hardest to get accurate transmission and reflection measurements when using a T/R network analyzer?A. Amplifiers because output power causes receiver compressionB. Cables because load match cannot be correctedC. Filter stopbands because
136、 of lack of dynamic rangeD. Mixers because of lack of broadband detectorsE. Attenuators because source match cannot be corrected9. Power sweeps are good for which measurements?A. Gain compressionB. AM to PM conversionC. Saturated output powerD. Power linearityE. All of the above111Network Analyzer BasicsAnswers to Challenge Quiz1. E2. C3. A4. B5. C6. A7. D8. B9. E112Network Analyzer Basics
