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Presented by: Beyond S-Parameters © Agilent Technologies, Inc. 2007 Agilent Back to Basic February, 2008 Measuring High-Frequency Networks and Components.

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Presentation on theme: "Presented by: Beyond S-Parameters © Agilent Technologies, Inc. 2007 Agilent Back to Basic February, 2008 Measuring High-Frequency Networks and Components."— Presentation transcript:

1 Presented by: Beyond S-Parameters © Agilent Technologies, Inc Agilent Back to Basic February, 2008 Measuring High-Frequency Networks and Components using Vector Network Analyzers Giovanni D’Amore

2 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 2 Objectives Understand what types of measurements are made with vector network analyzers (VNAs) Examine architectures of modern VNAs Provide insight into nonlinear characterization of amplifiers, mixers, and converters using a VNA Understand associated calibrations

3 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 3 What is a Vector Network Analyzer? Are stimulus-response test systems Characterize forward and reverse reflection and transmission responses (S-parameters) of RF and microwave components Quantify linear magnitude and phase Are very fast for swept measurements Provide the highest level of measurement accuracy S 21 S 12 S 11 S 22 R1 R2 RF Source LO Test port 2 B A Test port 1 Phase Magnitude DUT Reflection Transmission

4 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 4 What Types of Devices are Tested? Device type Active Passive Integration High Low Antennas Switches Multiplexers Mixers Samplers Multipliers Diodes Duplexers Diplexers Filters Couplers Bridges Splitters, dividers Combiners Isolators Circulators Attenuators Adapters Opens, shorts, loads Delay lines Cables Transmission lines Resonators Dielectrics R, L, C's RFICs MMICs T/R modules Transceivers Receivers Tuners Converters VCAs Amplifiers VTFs Modulators VCAtten’s Transistors

5 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 5 Device Test Measurement Model NF Stimulus type ComplexSimple Complex Response tool Simple DCCW Swept Swept Noise 2-toneMulti-tone Complex Pulsed- Protocol freq power modulation RF Det/Scope Param. An. NF Mtr. Imped. An. Power Mtr. SNA VNA SA VSA RFIC Testers TG/SA Ded. Testers I-V Absol. Power LCR/Z Harm. Dist. LO stability Image Rej. Gain/flat. Phase/GD Isolation Rtn loss Impedance S-parameters Compr'n AM-PM Mixers Balance d RFIC test Full call sequence Pulsed S-parm. Pulse profiling BER EVM ACP Regrowth Constell. Eye Intermodulation Distortion NF Measurement plane NF

6 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 6 Lightwave Analogy to RF Energy RF Incident Reflected Transmitted Lightwave DUT

7 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 7 Verify specifications of “building blocks” for more complex RF systems Ensure distortionless transmission of communications signals –linear: constant amplitude, linear phase / constant group delay –nonlinear: harmonics, intermodulation, compression Ensure good match when absorbing power (e.g., an antenna) Why Do We Need to Test Components?

8 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 8 The Need for Both Magnitude and Phase 4. Time-domain characterization Mag Time 5. Vector-error correction Error Measured Actual 2. Complex impedance needed to design matching circuits 3. Complex values needed for device modeling 1. Complete characterization of linear networks S 21 S 12 S 11 S 22

9 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 9 Agenda RECEIVER / DETECTOR PROCESSOR / DISPLAY REFLECTED (A) TRANSMITTED (B)INCIDENT (R) SIGNAL SEPARATION SOURCE Incident Reflected Transmitted DUT –What measurements do we make? Transmission-line basics Reflection and transmission parameters S-parameter definition –Network analyzer hardware Signal separation devices Detection types Dynamic range T/R versus S-parameter test sets –Error models and calibration Types of measurement error One- and two-port models Error-correction choices –Example measurements Filters Amplifiers Mixers/converters –Network Analyzers Portfolio SHORT OPEN LOAD

10 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 10 Transmission Line Basics Low frequencies l Wavelengths >> wire length l Current (I) travels down wires easily for efficient power transmission l Measured voltage and current not dependent on position along wire High frequencies l Wavelength  or << length of transmission medium l Need transmission lines for efficient power transmission l Matching to characteristic impedance (Z o ) is very important for low reflection and maximum power transfer l Measured envelope voltage dependent on position along line + _ I

11 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 11 Transmission line Z o Z o determines relationship between voltage and current waves Z o is a function of physical dimensions and  r Z o is usually a real impedance (e.g. 50 or 75 ohms) characteristic impedance for coaxial airlines (ohms) normalized values 50 ohm standard attenuation is lowest at 77 ohms power handling capacity peaks at 30 ohms

12 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 12 Power Transfer Efficiency RSRS RLRL For complex impedances, maximum power transfer occurs when ZL = ZS* (conjugate match) Maximum power is transferred when RL = RS R L / R S

13 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 13 Transmission Line Terminated with Zo For reflection, a transmission line terminated in Zo behaves like an infinitely long transmission line Zs = Zo Zo Vrefl = 0! (all the incident power is transferred to and absorbed in the load) V inc Zo = characteristic impedance of transmission line

14 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 14 Transmission Line Terminated with Short, Open Zs = Zo V refl V inc For reflection, a transmission line terminated in a short or open reflects all power back to source In-phase (0 o ) for open, out-of-phase (180 o ) for short

15 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 15 Transmission Line Terminated with 25 W V refl Standing wave pattern does not go to zero as with short or open Zs = Zo Z L = 25  V inc

16 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 16 High-Frequency Device Characterization Transmitted Incident TRANSMISSION Gain / Loss S-Parameters S 21, S 12 Group Delay Transmission Coefficient Insertion Phase Reflected Incident REFLECTION SWR S-Parameters S 11, S 22 Reflection Coefficient Impedance, Admittance R+jX, G+jB Return Loss   Incident Reflected Transmitted R B A A R = B R =

17 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 17 Reflection Parameters   dB No reflection (Z L = Zo)  RL VSWR 0 1 Full reflection (Z L = open, short) 0 dB 1  = Z L  Z O Z L + O Z Reflection Coefficient = V reflected V incident =    =   Return loss = -20 log(  ), Voltage Standing Wave Ratio VSWR = E max E min = 1 +  1 -  E max E min

18 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 18 Smith Chart Review  Smith Chart maps rectilinear impedance plane onto polar plane 0 +R +jX -jX Rectilinear impedance plane. -90 o 0 o 180 o o   Polar plane Z = Z o L = 0  Constant X Constant R Smith chart  L Z = 0 = ±180 O 1 (short) Z = L = 0 O 1  (open)

19 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 19 Transmission Parameters V Transmitted V Incident Transmission Coefficient =  = V Transmitted V Incident =  DUT Gain (dB) = 20 Log V Trans V Inc = 20 Log(  ) Insertion Loss (dB) = -20 Log V Trans V Inc = -20 Log(  )

20 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 20 Linear Versus Nonlinear Behavior Linear behavior: l Input and output frequencies are the same (no additional frequencies created) l Output frequency only undergoes magnitude and phase change Frequency f 1 Time Sin 360 o * f * t Frequency A phase shift = t o * 360 o * f 1 f DUT Time A t o A * Sin 360 o * f (t - t o ) InputOutput Time Nonlinear behavior: l Output frequency may undergo frequency shift (e.g. with mixers) l Additional frequencies created (harmonics, intermodulation) Frequency f 1

21 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 21 Criteria for Distortionless Transmission Constant amplitude over bandwidth of interest Magnitude Phase Frequency Linear phase over bandwidth of interest Linear Networks

22 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 22 Phase as a Function of Device Length At a Fixed Frequency, the Phase is a function of Device Length -360 O -720 O O O Phase  Degrees Length 1 m0.5 m Length Freq. = 1 GHz

23 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 23 Phase is also a Function of Frequency For a Fixed Device Length, the Phase is a function of Frequency -360 O -720 O O O Phase  Degrees Frequency 1 GHz0.5 GHz 1 meter

24 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 24 Displaying S21 in Phase Format CH1 S21Phase START GHz STOP GHz 100 O / REF 0 O Why does the Phase Response have a sawtooth waveform ?

25 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 25 CH1 S21Phase START GHz STOP GHz 100 O / REF 0 O Why does the Phase Response have a sawtooth waveform ? The Measured Phase is Displayed from 180 ° to -180° (Wrapped) The phase response is wrapped around 0 O covering the range +180 O to -180 O Slope of Phase Response Typical Phase Specs include Phase Length and Phase Linearity

26 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 26 High Resolution Deviation From Linear Phase Slope of Phase Response The Electrical Delay Feature Removes the Linear Slope from the Phase Response + = Inverse Slope of Phase Response Scale 100 O /Scale 5 O / Use Electrical Delay Feature Electrical Length added Now Measure the Phase Linearity

27 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 27 Group Delay in radians in radians/sec in degrees f in Hertz (  f)    Group Delay (t ) g =  d  d  = 11 360 o d  d f * Frequency Group delay ripple Average delay t o t g Phase   Frequency (   l Group-delay ripple indicates phase distortion l Average delay indicates electrical length of DUT l Aperture (  ) of measurement is very important

28 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 28 Why Measure Group Delay? Same peak-peak phase ripple can result in different group delay Phase Group Delay  d  d   d  d  f f f f

29 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 29 Characterizing Unknown Devices Using parameters (H, Y, Z, S) to characterize devices: l Gives linear behavioral model of our device l Measure parameters (e.g. voltage and current) versus frequency under various source and load conditions (e.g. short and open circuits) l Compute device parameters from measured data l Predict circuit performance under any source and load conditions H-parameters V 1 = h 11 I 1 + h 12 V 2 I 2 = h 21 I 1 + h 22 V 2 Y-parameters I 1 = y 11 V 1 + y 12 V 2 I 2 = y 21 V 1 + y 22 V 2 Z-parameters V 1 = z 11 I 1 + z 12 I 2 V 2 = z 21 I 1 + z 22 I 2 h 11 = V1V1 I1I1 V 2 =0 h 12 = V1V1 V2V2 I 1 =0 (requires short circuit) (requires open circuit)

30 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 30 Why Use S-Parameters? l Relatively easy to obtain at high frequencies n measure voltage traveling waves with a vector network analyzer n don't need shorts/opens which can cause active devices to oscillate or self-destruct l Relate to familiar measurements (gain, loss, reflection coefficient...) l Can cascade S-parameters of multiple devices to predict system performance l Can compute H, Y, or Z parameters from S-parameters if desired l Can easily import and use S-parameter files in our electronic-simulation tools Incident Transmitted S 21 S 11 Reflected S 22 Reflected Transmitted Incident b 1 a 1 b 2 a 2 S 12 DUT b 1 = S 11 a 1 + S 12 a 2 b 2 = S 21 a 1 + S 22 a 2 Port 1 Port 2

31 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 31 Measuring S-Parameters S 22 = Reflected Incident = b 2 a 2 a 1 = 0 S 12 = Transmitted Incident = b 1 a 2 a 1 = 0 S 11 = Reflected Incident = b 1 a 1 a 2 = 0 S 21 = Transmitted Incident = b 2 a 1 a 2 = 0 Transmitted S 21 S 11 Reflected b a 1 b 2 1 Z 0 Load a 2 = 0 DUT Forward IncidentTransmitted S 12 S 22 Reflected b 2 a 2 b a 1 = 0 DUT Z 0 Load Reverse 1

32 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 32 Equating S-Parameters with Common Measurement Terms S11 = 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 often express them in a log-magnitude format

33 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 33 Agenda RECEIVER / DETECTOR PROCESSOR / DISPLAY REFLECTED (A) TRANSMITTED (B)INCIDENT (R) SIGNAL SEPARATION SOURCE Incident Reflected Transmitted DUT –What measurements do we make? Transmission-line basics Reflection and transmission parameters S-parameter definition –Network analyzer hardware Signal separation devices Detection types Dynamic range T/R versus S-parameter test sets –Error models and calibration Types of measurement error One- and two-port models Error-correction choices Basic uncertainty calculations –Example measurements Filters Amplifiers Mixers/converters –Network Analyzers Portfolio SHORT OPEN LOAD

34 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 34 Generalized Network Analyzer Block Diagram (Forward Measurements) RECEIVER / DETECTOR PROCESSOR / DISPLAY REFLECTED (A) TRANSMITTED (B) INCIDENT (R) SIGNAL SEPARATION SOURCE Incident Reflected Transmitted DUT

35 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 35 Source l Supplies stimulus for system l Can sweep frequency or power l Traditionally NAs had one signal source l Modern NAs have option for two internal sources l Useful for two-signal measurements like IMD, phase versus drive l Can use second source as a local oscillator (LO) signal for mixers and converters PNA-X 26.5 GHz Network Analyzer RECEIVER / DETECTOR PROCESSOR / DISPLAY REFLECTED (A) TRANSMITTED (B)INCIDENT (R) SIGNAL SEPARATION SOURCE Incident Reflected Transmitted DUT

36 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 36 Signal Separation Test Port Detector directional coupler splitter bridge Measure incident signal for reference Separate incident and reflected signals RECEIVER / DETECTOR PROCESSOR / DISPLAY REFLECTED (A) TRANSMITTED (B)INCIDENT (R) SIGNAL SEPARATION SOURCE Incident Reflected Transmitted DUT

37 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 37 Directivity Directivity is a measure of how well a coupler can separate signals moving in opposite directions Test port (undesired leakage signal) (desired reflected signal) Directional Coupler desired leakage result Directivity = Isolation (I) - Fwd Coupling (C) - Main Arm Loss (L) IC L

38 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 38 Interaction of Directivity with the DUT (Without Error Correction) Data max Add in-phase Device Directivity Return Loss Frequency DUT RL = 40 dB Add out-of-phase (cancellation) Device Directivity Data = vector sum Directivity Device Data min

39 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 39 Detector Types Tuned Receiver Scalar broadband (no phase information) Vector (magnitude and phase) Diode AC DC RF IF Filter IF = F LO F RF  LO ADC / DSP RECEIVER / DETECTOR PROCESSOR / DISPLAY REFLECTED (A) TRANSMITTED (B)INCIDENT (R) SIGNAL SEPARATION SOURCE Incident Reflected Transmitted DUT

40 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 40 Broadband Diode Detection l Easy to make broadband l Inexpensive compared to tuned receiver l Good for measuring frequency-translating devices l Improve dynamic range by increasing power l Medium sensitivity / dynamic range 10 MHz 26.5 GHz

41 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 41 Narrowband Detection - Tuned Receiver l Best sensitivity / dynamic range l Provides harmonic / spurious signal rejection l Improve dynamic range by increasing power, decreasing IF bandwidth, or averaging l Trade off noise floor and measurement speed 10 MHz 26.5 GHz IF Filter LO ADC / DSP RF

42 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 42 Comparison of Receiver Techniques < -100 dBm Sensitivity 0 dB -50 dB -100 dB 0 dB -50 dB -100 dB -60 dBm Sensitivity Broadband (diode) detection Narrowband (tuned-receiver) detection l Higher noise floor l False responses l High dynamic range l Harmonic immunity Dynamic range = maximum receiver power - receiver noise floor

43 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 43 T/R Versus S-Parameter Test Sets l RF comes out port 1; port 2 is receiver l Forward measurements only l Response, one-port cal available l RF comes out port 1 or port 2 l Forward and reverse measurements l Two-port calibration possible Transmission/Reflection Test Set Port 1Port 2 Source B R A DUT Fwd S-Parameter Test Set DUT FwdRev Port 1 Transfer switch Port 2 Source B R1 A R2 Fwd

44 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 44 ENA Analog Block Diagram: Receiver

45 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 45 Modern VNA Block Diagram (2-Port PNA-X) Test port 1 Test port 2 R2 35 dB 65 dB Rear panel A 35 dB B Source 2 Output 1 Source 2 Output 2 Noise receivers 10 MHz - 3 GHz GHz DU T Pulse generators RF jumpers Receivers Mechanical switch Source 1 OUT 2 OUT 1 Pulse modulator LO To receivers R1 OUT 1 OUT 2 Pulse modulator J11J10J9J8J7J2J1 ECal used as impedance tuner for noise figure measurements

46 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 46 RECEIVER / DETECTOR PROCESSOR / DISPLAY REFLECTED (A) TRANSMITTED (B) INCIDENT (R) SIGNAL SEPARATION SOURCE Incident Reflected Transmitted DUT Processor / Display l Markers l Limit lines l Pass/fail indicators l Linear/log formats l Grid/Polar/Smith charts

47 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 47 Achieving measurement flexibility Channel Trace Parameter Format Scale Markers Trace math Electrical delay Phase offset Smoothing Limit tests Time-domain transform Channel Sweep type Frequencies Power level IF bandwidth Number of points Trigger state Averaging Calibration Window Trace (CH1) Trace (CH2) Trace (CH1) Trace (CH2) Trace (CH3) Trace (CH4)

48 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 48 Three channel example Window Channel 1 frequency sweep (narrow) S11S21 Channel 2 frequency sweep (broad) S21 Channel 3 power sweep S21S11

49 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 49 Internal Measurement Automation Simple: Recall States More powerful: –Windows-compatible programs Available on PNA Series Visual Basic, VEE, LabView, C++,... –Visual Basic for Applications Available on ENA Series Visual Basic for Applications on ENA

50 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 50 Agenda RECEIVER / DETECTOR PROCESSOR / DISPLAY REFLECTED (A) TRANSMITTED (B)INCIDENT (R) SIGNAL SEPARATION SOURCE Incident Reflected Transmitted DUT –What measurements do we make? Transmission-line basics Reflection and transmission parameters S-parameter definition –Network analyzer hardware Signal separation devices Detection types Dynamic range T/R versus S-parameter test sets –Error models and calibration Types of measurement error One- and two-port models Error-correction choices –Example measurements Filters Amplifiers Mixers/converters –Network Analyzers Portfolio SHORT OPEN LOAD

51 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 51 The Need For Calibration Why do we have to calibrate? –It is impossible to make perfect hardware –It would be extremely difficult and expensive to make hardware good enough to entirely eliminate the need for error correction How do we get accuracy? –With vector-error-corrected calibration –Not the same as the yearly instrument calibration What does calibration do for us? –Removes the largest contributor to measurement uncertainty: systematic errors –Provides best picture of true performance of DUT Systematic error

52 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 52 Measurement Error Modeling Systematic errors Due to imperfections in the analyzer and test setup Assumed to be time invariant (predictable) Generally, are largest sources or error Random errors Vary with time in random fashion (unpredictable) Main contributors: instrument noise, switch and connector repeatability Drift errors Due to system performance changing after a calibration has been done Primarily caused by temperature variation CAL RE-CAL Measured Data SYSTEMATIC RANDOM DRIFT Errors: Unknown Device

53 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 53 Systematic Measurement Errors AB Source Mismatch Load Mismatch Crosstalk Directivity DUT Frequency response l Reflection tracking (A/R) l Transmission tracking (B/R) R Six forward and six reverse error terms yields 12 error terms for two-port devices

54 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 54 Types of Error Correction l Response (normalization) – Simple to perform – Only corrects for tracking (frequency response) errors – Stores reference trace in memory, then does data divided by memory l Vector – Requires more calibration standards – Requires an analyzer that can measure phase – Accounts for all major sources of systematic error S 11 m S a SHORT OPEN LOAD thru

55 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 55 What is Vector-Error Correction? Vector-error correction… Is a process for characterizing systematic error terms Measures known electrical standards Removes effects of error terms from subsequent measurements Electrical standards… Can be mechanical or electronic Are often an open, short, load, and thru, but can be arbitrary impedances as well Errors Measured Actual

56 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 56 Using Known Standards to Correct for Systematic Errors l 1-port calibration (reflection measurements) n Only three systematic error terms measured n Directivity, source match, and reflection tracking l Full two-port calibration (reflection and transmission measurements) n Twelve systematic error terms measured n Usually requires 12 measurements on four known standards (SOLT) l Standards defined in cal kit definition file n Network analyzer contains standard cal kit definitions n CAL KIT DEFINITION MUST MATCH ACTUAL CAL KIT USED! n User-built standards must be characterized and entered into user cal-kit

57 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 57 Reflection: One-Port Model E D = Directivity E RT = Reflection tracking E S = Source Match S11 M = Measured S11 A = Actual To solve for error terms, we measure 3 standards to generate 3 equations and 3 unknowns S 11 M S 11 A ESES E RT EDED 1 RF in Error Adapter S 11 M S 11 A RF in Ideal l Assumes good termination at port two if testing two-port devices l If using port two of NA and DUT reverse isolation is low (e.g., filter passband): n Assumption of good termination is not valid n Two-port error correction yields better results S 11M = E D + E RT 1 - E S S 11A S 11A

58 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 58 Before and After One-Port Calibration data before 1-port calibration data after 1-port calibration Return Loss (dB) VSWR MHz

59 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 59 Two-Port Error Correction l Each actual S-parameter is a function of all four measured S-parameters l Analyzer must make forward and reverse sweep to update any one S-parameter l Luckily, you don't need to know these equations to use a network analyzers!!! Port 1Port 2 E S 11 S 21 S 12 S 22 E S E D E RT E TT E L a 1 b 1 A A A A X a 2 b 2 Forward model = fwd directivity = fwd source match = fwd reflection tracking = fwd load match = fwd transmission tracking = fwd isolation E S E D E RT E TT E L E X = rev reflection tracking = rev transmission tracking = rev directivity = rev source match = rev load match = rev isolation E S' E D' E RT' E TT' E L' E X' Port 1Port 2 S 11 S S 12 S 22 E S' E D' E RT' E TT' E L' a 1 b 1 A A A E X' 21 A a 2 b 2 Reverse model

60 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 60 Errors and Calibration Standards l Convenient l Generally not accurate l No errors removed l Easy to perform l Use when highest accuracy is not required l Removes frequency response error l For reflection measurements l Need good termination for high accuracy with two-port devices l Removes these errors: Directivity Source match Reflection tracking l Highest accuracy l Removes these errors: Directivity Source, load match Reflection tracking Transmission tracking Crosstalk UNCORRECTED RESPONSE 1-PORT FULL 2-PORT DUT thru ENHANCED-RESPONSE l Combines response and 1-port l Corrects source match for transmission measurements SHORT OPEN LOAD SHORT OPEN LOAD SHORT OPEN LOAD

61 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 61 Response versus Two-Port Calibration CH1 S 21 &M log MAG 1 dB/REF 0 dB Cor CH2 MEM log MAG REF 0 dB 1 dB/ Cor Uncorrected After two-port calibration START MHz STOP MHz x2 12 After response calibration Measuring filter insertion loss

62 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 62 Calibration Summary error cannot be corrected * enhanced response cal corrects for source match during transmission measurements error can be corrected SHORT OPEN LOAD l Reflection tracking l Directivity l Source match l Load match S-parameter (two-port) T/R (one-port) Reflection Test Set (cal type) l Transmission Tracking l Crosstalk l Source match l Load match S-parameter (two-port) T/R (response, isolation) Transmission Test Set (cal type) * ( )

63 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 63 Variety of two- and four-port modules cover 300 kHz to 67 GHz Nine connector types available, 50 and 75 ohms Single-connection calibrations n dramatically reduces calibration time n makes calibrations easy to perform n minimizes wear on cables and standards n eliminates operator errors Highly repeatable temperature-compensated characterized terminations provide excellent accuracy ECal: Electronic Calibration Microwave modules use a transmission line shunted by PIN-diode switches in various combinations USB controlled

64 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 64 ECAL User Characterization 4. NA stores resulting characterization data inside the module. 2. Perform a calibration using appropriate mechanical standards. 3. Measure the ECal module, including adapters, as though it were a DUT 1. Select adapters for the module to match the connector configuration of the DUT.

65 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 65 Thru-Reflect-Line (TRL) Calibration We know about Short-Open-Load-Thru (SOLT) calibration... What is TRL? l A two-port calibration technique l Good for non-coaxial environments (waveguide, fixtures, wafer probing) l Characterizes same 12 systematic errors as the more common SOLT cal l Uses practical calibration standards that are easily fabricated and characterized l Other variations: Line-Reflect-Match (LRM), Thru-Reflect-Match (TRM), plus many others TRL was developed for non- coaxial microwave measurements

66 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 66 Advanced Calibration Techniques for Mixers/Converters Vector Mixer Calibration (VMC) Most accurate measurements of phase and absolute group delay Removes magnitude and phase errors for transmission and reflection measurements by calibrating with characterized through mixer DUT Reference mixer Power meter Calibration mixer/filter Conversion loss and match Conversion loss, delay, and match DUT GPIB Simple setup with no external signal source Match correction ELIMINATES ATTENUATORS! Simple setup with no external signal source Match correction ELIMINATES ATTENUATORS! Scalar Mixer Calibration (SMC) Highest accuracy conversion-loss measurements with simple setup and cal Removes mismatch errors during calibration and measurements by combining one-port and power-meter calibrations

67 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 67 Agenda RECEIVER / DETECTOR PROCESSOR / DISPLAY REFLECTED (A) TRANSMITTED (B)INCIDENT (R) SIGNAL SEPARATION SOURCE Incident Reflected Transmitted DUT –What measurements do we make? Transmission-line basics Reflection and transmission parameters S-parameter definition –Network analyzer hardware Signal separation devices Detection types Dynamic range T/R versus S-parameter test sets –Error models and calibration Types of measurement error One- and two-port models Error-correction choices Basic uncertainty calculations –Example measurements Filters Amplifiers Mixers/converters –Network Analyzers Portfolio SHORT OPEN LOAD

68 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 68 Frequency Sweep - Filter Test Input and output return loss 65 dB Stopband rejection Insertion loss, flatness/ripple, and group delay Out-of-band isolation/rejection

69 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 69 Segment 3: 29 ms (108 points, -10 dBm, 6000 Hz) Optimize Filter Measurements with Swept-List Mode CH1S 21 log MAG12 dB/REF 0 dB START MHz PRm PASS STOP MHz Segment 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 pts, 300 Hz, -10 dBm) Segment sweep: 349 ms (201 pts, variable BW's & power)

70 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 70 Common Amplifier Measurements Gain, gain flatness, deviation from linear phase, group delay Complex Stimulus response ACPR/EVM, BER, CCDF Reverse isolation Return loss/SWR K-factor Linear measurements Non-linear measurements Return loss/SWR Compression, AM/PM conversion, harmonic distortion, intermodulation distortion (IMD/TOI) Noise figure

71 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 71 Power Sweeps - Compression Saturated output power Output Power (dBm) Input Power (dBm) Compression region Linear region (slope = small-signal gain) Gain (S21) Input power (R1) Output power (B)

72 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 72 AM to PM Conversion AM to PM Conversion = Mag(PM out ) Mag(AM in ) (deg/dB) DUT Amplitude Time AM (dB) PM (deg) Mag(AM out ) Mag(Pm out ) Output Response Amplitude Time AM (dB) PM (deg) Mag(Am in ) Test Stimulus Power sweep I Q AM to PM conversion can cause bit errors Measure of phase deviation caused by amplitude variations l AM can be undesired: supply ripple, fading, thermal l AM can be desired: modulation (e.g. QAM)

73 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 73 Measuring AM to PM Conversion l Use transmission setup with a power sweep l Display phase of S21 l Use delta markers to calculate delta power and delta phase 1 dB compression point AM-PM = 0.743/1.05 =.71 deg/dB

74 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 74 Nonlinear Testing With One Source – Harmonics Sweep fundamental frequency Measure harmonics generated by DUT VNA must be able to tune receivers independent of stimulus (frequency-offset mode) 2xf 1 f1f1 Tune receiver to 2xf 1 DUT Stimulus 2 nd harmonic example

75 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 75 Easily Switch Between One- and Two-Source Tests

76 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 76 Swept-frequency IMDSwept-power IMD Nonlinear Testing With Two Sources – Swept IMD fundamental signals IMD (IM3) products Intercept point (IP3/TOI)

77 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 77 Mixer Component - Measuring Conversion Loss A f IF RF LO Conversion Loss Swept IF Fixed IF A f IF RF LO Conversion Loss Conversion loss dB = (Function of LO power) mag(f in ) W mag(f out ) W 10 log RF LO IF f1 f2 f3 f1 + f2 f1 - f2

78 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 78 Mixer/Converter Measurements Fixed LO Swept IF Swept LO Fixed IF DUT Second source used as LO signal

79 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 79 Noise Figure Definition Noise figure is defined in terms of SNR degradation: F = (S o /N o ) (S i /N i ) = (N o ) (G x N i ) (noise factor) NF = 10 x log (F)(noise figure) DUT S o /N o S i /N i Gain

80 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 80 Measuring Noise Figure with a VNA PNA-X uses modified cold-source technique: Basic idea: measure S21 and then noise power at output of amplifier Enhancement: use ECal as impedance tuner to correct noise-parameter effects due to imperfect system source match Measure key amplifier parameters with a single connection (e.g. S-parameters, noise figure, compression, IMD, harmonics) Achieve the highest measurement accuracy of any solution on the market DUT Noise Receiver Tuner

81 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 81 Summary High frequency component characterization requires special equipment and techniques Vector network analyzers (VNAs) are a key tool to measure both linear and non-linear behavior of networks and components Modern VNAs perform a variety of measurements beyond basic S-parameters (compression, IMD, harmonics, noise figure …) Calibration is important to obtain accurate measurements

82 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 82 Agilent Network analyzer Portfolio 6 GHz 13.5 GHz 20 GHz 40 GHz 50 GHz 67 GHz 110 GHz 325 GHz 500 GHz

83 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 83 The network analyzer portfolio from Agilent delivers an unparalleled combination of performance and flexibility for a broad range of applications from 9 kHz up to 500 GHz! ENA Series - RF 8.5 GHz 4.5 GHz 1.5 GHz PNA Series - Microwave Agilent: World Leader in Network Analysis 6 GHz 13.5 GHz 20 GHz 40 GHz 50 GHz 67 GHz 110 GHz 325 GHz 26.5 GHz 500 GHz

84 Beyond S-Parameters © Agilent Technologies, Inc Aerospace and Defense Symposium 2007 Agilent Back to Basic February, Agilent Back to Basic Page M6- 84 Portfolio Comparison PNA-L High Performance Basic Measurements & Entry Level General Purpose PNA-X PNA ENA-L ENA 4.5GHz8.5GHz 1.5GHz3GHz 6GHz 20GHz 40GHz 20GHz40GHz50GHz 26.5 GHz 67GHz 13.5GHz 50GHz


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