1、Network Analyzer BasicsNetwork Analysis is NOT.RouterBridgeRepeaterHubYour IEEE 802.3 X.25 ISDN switched-packet data stream is running at 147 MBPS with a BER of 1.523 X 10 . . . -9What Types of Devices are Tested?Device typeActivePassiveIntegrationHighLowAntennasSwitchesMultiplexersMixersSamplersMul
2、tipliersDiodesDuplexersDiplexersFiltersCouplersBridgesSplitters, dividersCombinersIsolatorsCirculatorsAttenuatorsAdaptersOpens, shorts, loadsDelay linesCablesTransmission linesWaveguideResonatorsDielectricsR, L, CsRFICsMMICsT/R modulesTransceiversReceiversTunersConvertersVCAsAmplifiersVCOsVTFsOscill
3、atorsModulatorsVCAttensTransistorsDevice Test Measurement ModelNFStimulus typeComplexSimpleComplexResponse toolSimpleDCCW Swept Swept Noise 2-tone Multi- Complex Pulsed- Protocol freq power tone modulation RFDet/ScopeParam. An.NF Mtr.Imped. An.Power Mtr.SNAVNASAVSA84000TG/SADed. TestersI-VAbsol. Pow
4、erGain/FlatnessLCR/ZHarm. Dist.LO stabilityImage Rej.Gain/Flat.Phase/GDIsolationRtn Ls/VSWRImpedanceS-parametersComprnAM-PMRFIC testFull call sequencePulsed S-parm.Pulse profilingBEREVMACPRegrowthConstell.EyeIntermodulation DistortionNFMeasurement planeLightwave Analogy to RF Energy RFIncidentReflec
5、tedTransmitted LightwaveDUTWhy Do We Need to Test Components?Verify specifications of “building blocks” for more complex RF systemsEnsure distortionless transmission of communications signals linear: constant amplitude, linear phase / constant group delay nonlinear: harmonics, intermodulation, compr
6、ession, AM-to-PM conversionEnsure good match when absorbing power (e.g., an antenna)KPW RFM 97The 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
7、device modeling 1. Complete characterization of linear networks High-frequency transistor model CollectorBaseEmitterS21S12S11S22AgendalWhat measurements do we make?Transmission-line basicsReflection and transmission parametersS-parameter definitionlNetwork analyzer hardwareSignal separation devicesD
8、etection typesDynamic rangeT/R versus S-parameter test setslError models and calibrationTypes of measurement errorOne- and two-port modelsError-correction choicesBasic uncertainty calculationslExample measurementslAppendixTransmission Line BasicsLow frequencieslwavelengths wire lengthlcurrent (I) tr
9、avels 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 characteristic impedance (Zo) is very important
10、for low reflection and maximum power transferlmeasured envelope voltage dependent on position along lineI+-Transmission line ZoZo determines relationship between voltage and current wavesZo is a function of physical dimensions and r Zo is usually a real impedance (e.g. 50 or 75 ohms)characteristic i
11、mpedancefor coaxial airlines (ohms)102030405060 708090 1001.00.80.70.60.50.91.51.41.31.21.1normalized values50 ohm standardattenuation is lowest at 77 ohmspower handling capacity peaks at 30 ohmsPower Transfer EfficiencyRSRLFor complex impedances, maximum power transfer occurs when ZL = ZS* (conjuga
12、te match)Maximum power is transferred when RL = RSRL / RS00.20.40.60.811.2012345678910Load Power (normalized) RsRL+jX-jXTransmission Line Terminated with Zo For reflection, a transmission line terminated in Zo behaves like an infinitely long transmission lineZs = ZoZoVrefl = 0! (all the incident pow
13、er is absorbed in the load)VincZo = characteristic impedance of transmission lineTransmission Line Terminated with Short, Open Zs = ZoVreflVincFor reflection, a transmission line terminated in a short or open reflects all power back to sourceIn-phase (0o) for open, out-of-phase (180o) for shortTrans
14、mission Line Terminated with 25 W VreflStanding wave pattern does not go to zero as with short or openZs = ZoZL = 25 WVincHigh-Frequency Device CharacterizationTransmittedIncidentTRANSMISSIONGain / LossS-ParametersS21, S12GroupDelayTransmissionCoefficientInsertion PhaseReflectedIncidentREFLECTIONSWR
15、S-ParametersS11, S22ReflectionCoefficientImpedance, Admittance R+jX, G+jB ReturnLoss G, rT,tIncidentReflectedTransmittedRBAAR=BR=Reflection Parameters dBNo reflection(ZL = Zo)r rRLVSWR01Full reflection(ZL = open, short)0 dB1=ZL-ZOZL+OZReflection Coefficient=VreflectedVincident=rFG=rGReturn loss = -2
16、0 log(r),Voltage Standing Wave RatioVSWR = EmaxEmin=1 + r1 - rEmaxEminSmith 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 O
17、1G(open) Transmission ParametersVTransmittedVIncidentTransmission Coefficient = T=VTransmittedVIncident = tfDUTGain (dB) = 20 Log VTrans VInc = 20 log tInsertion Loss (dB) = - 20 Log VTrans VInc = - 20 log tLinear Versus Nonlinear BehaviorLinear behavior:linput and output frequencies are the same (n
18、o additional frequencies created)loutput frequency only undergoes magnitude and phase changeFrequencyf1TimeSin 360o * f * tFrequencyA phase shift = to * 360o * f1fDUTTimeAto A * Sin 360o * f (t - to)InputOutputTimeNonlinear behavior:loutput frequency may undergo frequency shift (e.g. with mixers)lad
19、ditional frequencies created (harmonics, intermodulation)Frequencyf1Criteria for Distortionless Transmission Linear NetworksConstant amplitude over bandwidth of interestMagnitudePhaseFrequencyFrequencyLinear phase over bandwidth of interestMagnitude Variation with FrequencyF(t) = sin wt + 1/3 sin 3w
20、t + 1/5 sin 5wtTimeLinear NetworkFrequencyFrequencyFrequencyMagnitudeTimePhase Variation with FrequencyFrequencyMagnitudeLinear NetworkFrequencyFrequencyTime0-180-360TimeF(t) = sin wt + 1 /3 sin 3wt + 1 /5 sin 5wtDeviation from Linear Phase Use electrical delay to remove linear portion of phase resp
21、onseLinear electrical length added+yieldsFrequency(Electrical delay function)FrequencyRF filter responseDeviation from linear phasePhase 1 /DivoPhase 45 /DivoFrequencyLow resolutionHigh resolutionGroup Delayin radiansin radians/secin degreesf in Hertz (w = 2 p f)f fwfGroup Delay (t )g =- -d f fd w=-
22、1360od fd f*FrequencyGroup delay rippleAverage delaytotgPhasefDfFrequencyDwwlgroup-delay ripple indicates phase distortionlaverage delay indicates electrical length of DUTlaperture of measurement is very importantWhy Measure Group Delay?Same p-p phase ripple can result in different group delayPhaseP
23、haseGroup DelayGroup Delay- -d f fd w w- -d f fd w wffffCharacterizing Unknown DevicesUsing parameters (H, Y, Z, S) to characterize devices:lgives linear behavioral model of our devicelmeasure parameters (e.g. voltage and current) versus frequency under various source and load conditions (e.g. short
24、 and open circuits)lcompute device parameters from measured datalpredict circuit performance under any source and load conditionsH-parametersV1 = h11I1 + h12V2I2 = h21I1 + h22V2Y-parametersI1 = y11V1 + y12V2I2 = y21V1 + y22V2Z-parametersV1 = z11I1 + z12I2V2 = z21I1 + z22I2h11 = V1I1V2=0h12 = V1V2I1=
25、0(requires short circuit)(requires open circuit)Why Use S-Parameters?lrelatively easy to obtain at high frequenciesnmeasure voltage traveling waves with a vector network analyzerndont need shorts/opens which can cause active devices to oscillate or self-destructlrelate to familiar measurements (gain
26、, loss, reflection coefficient .)lcan cascade S-parameters of multiple devices to predict system performancelcan compute H, Y, or Z parameters from S-parameters if desiredlcan easily import and use S-parameter files in our electronic-simulation toolsIncidentTransmittedS21S11ReflectedS22ReflectedTran
27、smittedIncidentb1a1b2a2S12DUTb1= S11a1+ S12a2b2= S21a1+ S22a2Port 1Port 2Measuring S-ParametersS11=ReflectedIncident=b1a1a2= 0S21=TransmittedIncident=b2a1a2= 0S22=ReflectedIncident=b2a2a1= 0S12=TransmittedIncident=b1a2a1= 0IncidentTransmittedS21S11Reflectedb1a1b2Z0Loada2= 0DUTForwardIncidentTransmit
28、tedS12S22Reflectedb2a2ba1= 0DUTZ0LoadReverse1Equating S-Parameters with Common Measurement TermsS11 = forward reflection coefficient (input match)S22 = reverse reflection coefficient (output match)S21 = forward transmission coefficient (gain or loss)S12 = reverse transmission coefficient (isolation)
29、Remember, S-parameters are inherently complex, linear quantities - however, we often express them in a log-magnitude formatFrequencyFrequencyTimeTimeCriteria for Distortionless Transmission Nonlinear NetworksSaturation, crossover, intermodulation, and other nonlinear effects can cause signal distort
30、ionEffect on system depends on amount and type of distortion and system architectureMeasuring Nonlinear BehaviorMost common measurements:lusing a network analyzer and power sweepsgain compressionAM to PM conversionlusing a spectrum analyzer + source(s)harmonics, particularly second and thirdintermod
31、ulation products resulting from 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 GHzLPFDUTWhat is the Difference Between Network and Spectrum alyzers?.Amplitude RatioFrequency AmplitudeFrequenc
32、y8563ASPECTRUM 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
33、:lmeasure signal amplitude characteristicscarrier level, sidebands, harmonics.)lcan demodulate (& measure) complex signalslare receivers only (single channel)lcan be used for scalar component test (no phase) with tracking gen. or ext. source(s)AgendalWhat measurements do we make?lNetwork analyzer ha
34、rdwarelError models and calibrationlExample measurementslAppendixGeneralized Network Analyzer Block DiagramRECEIVER / DETECTORPROCESSOR / DISPLAYREFLECTED(A)TRANSMITTED(B)INCIDENT (R)SIGNALSEPARATIONSOURCEIncidentReflectedTransmittedDUTSourcelSupplies stimulus for systemlSwept frequency or powerlTra
35、ditionally NAs used separate sourcelMost Agilent analyzers sold today have integrated, synthesized sourcesSignal SeparationTest PortDetectordirectional couplersplitterbridgemeasure incident signal for referenceseparate incident and reflected signalsRECEIVER / DETECTORPROCESSOR / DISPLAYREFLECTED(A)T
36、RANSMITTED(B)INCIDENT (R)SIGNALSEPARATIONSOURCEIncidentReflectedTransmittedDUTDirectivityDirectivity is a measure of how well a coupler can separate signals moving in opposite directionsTest port(undesired leakage signal)(desired reflected signal)Directional CouplerInteraction of Directivity with th
37、e DUT (Without Error Correction)Data MaxAdd in-phaseDeviceDirectivityReturn LossFrequency03060DUT RL = 40 dBAdd out-of-phase (cancellation)DeviceDirectivityData = Vector SumDirectivityDeviceData MinDetector TypesTuned ReceiverScalar broadband (no phase information)Vector(magnitude and phase)DiodeDCA
38、CRFIF FilterIF = F LOFRFRFLOADC / DSPRECEIVER / DETECTORPROCESSOR / DISPLAYREFLECTED(A)TRANSMITTED(B)INCIDENT (R)SIGNALSEPARATIONSOURCEIncidentReflectedTransmittedDUTBroadband Diode DetectionlEasy to make broadbandlInexpensive compared to tuned receiverlGood for measuring frequency-translating devic
39、eslImprove dynamic range by increasing powerlMedium sensitivity / dynamic range10 MHz26.5 GHzNarrowband Detection - Tuned ReceiverlBest sensitivity / dynamic rangelProvides harmonic / spurious signal rejectionlImprove dynamic range by increasing power, decreasing IF bandwidth, or averaginglTrade off
40、 noise floor and measurement speed10 MHz26.5 GHzADC / DSPComparison 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 immuni
41、tyDynamic range = maximum receiver power - receiver noise floorDynamic Range and AccuracyDynamic range is very important for measurement accuracy!phase errormagn error+-T/R Versus S-Parameter Test SetslRF always comes out port 1lport 2 is always receiverlresponse, one-port cal availablelRF comes out
42、 port 1 or port 2lforward and reverse measurementsltwo-port calibration possibleTransmission/Reflection Test SetPort 1Port 2SourceBRADUTFwdPort 1Port 2Transfer switchSourceBRAS-Parameter Test SetDUTFwdRevRECEIVER / DETECTORPROCESSOR / DISPLAYREFLECTED(A)TRANSMITTED(B)INCIDENT (R)SIGNALSEPARATIONSOUR
43、CEIncidentReflectedTransmittedDUTProcessor / DisplayCH1 S21 log MAG10 dB/REF 0 dBCH1 START 775.000 000 MHzSTOP 925.000 000 MHz CorHldPRmCH2 S12 log MAGREF 0 dB10 dB/CH2 START 775.000 000 MHzSTOP 925.000 000 MHz Duplexer Test - Tx-Ant and Ant-RxCorHldPRm 111_ -1.9248 dB 839.470 000 MHz PASS211_ -1.24
44、68 dB 880.435 000 MHz PASSlmarkersllimit lineslpass/fail indicatorsllinear/log formatslgrid/polar/Smith chartsACTIVE CHANNELRESPONSESTIMULUSENTRYINSTRUMENT STATE R CHANNELR LTSHP-IB STATUSNETWORK ANYZER50 MH-20GHzPORT 2PORT 1CH1 S21 log MAG10 dB/REF 0 dBCH1 START 775.000 000 MHzSTOP 925.000 000 MHz
45、CorHldPRmCH2 S12 log MAGREF 0 dB10 dB/CH2 START 775.000 000 MHzSTOP 925.000 000 MHz Duplexer Test - Tx-Ant and Ant-RxCorHldPRm 111_ -1.9248 dB 839.470 000 MHz PASS211_ -1.2468 dB 880.435 000 MHz PASSInternal Measurement AutomationSimple: recall statesMore powerful:lTest sequencingnavailable on 8753/
46、 8720 familiesnkeystroke recordingnsome advanced functionslIBASICnavailable on 8712 familynsophisticated programsncustom user interfacesnWindows-compatible programsnavailable on PNA SeriesnVisual Basic, VEE, LabView, C+, .ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789 + - / * = ( ) & , . / ? ; : 1 ASSIGN Hp87
47、14 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:WIND1:TRAC:Y
48、: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;ABOR;:INIT1:
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