Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Electromagnetic compatibility wikipedia , lookup
Quality of service wikipedia , lookup
History of electric power transmission wikipedia , lookup
Transmission line loudspeaker wikipedia , lookup
Telecommunications engineering wikipedia , lookup
Computer network wikipedia , lookup
Rectiverter wikipedia , lookup
Two-port network wikipedia , lookup
Network Analyzer Basics Network Analyzer Basics Network Analysis is NOT.… Router Bridge Repeater Hub Your IEEE 802.3 X.25 ISDN switched-packet data stream is running at 147 MBPS with -9 a BER of 1.523 X 10 . . . Network Analyzer Basics Network Analyzer Basics Low Dielectrics R, L, C's Passive Complex RFICs MMICs T/R modules Transceivers VSA SA Receivers Tuners Converters VCAs Amplifiers Antennas Switches Multiplexers Mixers Samplers Multipliers Diodes Device type VCOs VTFs Oscillators Modulators VCAtten’s RFIC test Harm. Dist. LO stability Image Rej. VNA TG/SA SNA NF Mtr. Param. An. Power Mtr. Transistors Det/Scope Full call sequence Pulsed S-parm. Pulse profiling NF LCR/Z I-V Measurement plane Absol. Power Gain/Flatness DC CW Swept Swept freq power modulation RF Simple Active Intermodulation Distortion NF BER EVM ACP Regrowth Constell. Eye Gain/Flat. Compr'n Phase/GD AM-PM Isolation Rtn Ls/VSWR Impedance S-parameters Imped. An. Network Analyzer Basics Noise 2-tone Multi- Complex tone Pulsed- Stimulus type Protocol Complex Network Analyzer Basics Lightwave Analogy to RF Energy Incident Reflected 84000 Ded. Testers Response tool Integration Duplexers Diplexers Filters Couplers Bridges Splitters, dividers Combiners Isolators Circulators Attenuators Adapters Opens, shorts, loads Delay lines Cables Transmission lines Waveguide Resonators Device Test Measurement Model Simpl e High What Types of Devices are Tested? Why Do We Need to Test Components? • Verify specifications of “building blocks” for more complex RF systems • Ensure distortionless transmission of communications signals Transmitted – linear: constant amplitude, linear phase / constant group delay – nonlinear: harmonics, intermodulation, compression, AMto-PM conversion Lightwave • Ensure good match when absorbing power (e.g., an antenna) DUT RF KPWR Network Analyzer Basics Network Analyzer Basics 1 FM 97 Network Analyzer Basics The Need for Both Magnitude and Phase Agenda S21 1. Complete characterization of linear networks S11 S22 S12 2. Complex impedance needed to design matching circuits 4. Time-domain characterization Mag 3. Complex values needed for device modeling High-frequency transistor model Time 5. Vector-error correction Error Base Collector Measured 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 Appendix Actual Emitter Network Analyzer Basics Network Analyzer Basics Transmission line Zo Transmission Line Basics - I • • • Zo determines relationship between voltage and current waves Zo is a function of physical dimensions and εr Zo is usually a real impedance (e.g. 50 or 75 ohms) 1.5 Twisted-pair 1.3 a 1.2 b High frequencies wavelength ≈ or << length of transmission medium need transmission lines for efficient power transmission matching to characteristic impedance (Z o) is very important for low reflection and maximum Network Analyzer Basics power transfer measured envelope voltage dependent on εr Coaxial w2 Coplanar 50 ohm standard 1.0 0.9 0.8 power handling capacity peaks at 30 ohms 0.6 w 0.5 10 20 30 40 50 60 70 80 90 100 characteristic impedance for coaxial airlines (ohms) Microstrip Network Analyzer Basics Transmission Line Terminated with Zo Zs = Zo Load Power (normalized) 1.1 0.7 w1 RS For complex impedances, maximum power transfer occurs when ZL = ZS* (conjugate match) Rs 1.2 h h Power Transfer Efficiency RL attenuation is lowest at 77 ohms 1.4 Waveguide normalized values + Low frequencies wavelengths >> wire length current (I) travels down wires easily for efficient power transmission measured voltage and current not dependent on position along wire Zo = characteristic impedance of transmission line Zo +jX 1 -jX 0.8 Vinc 0.6 RL 0.4 0.2 Vrefl = 0! (all the incident power is absorbed in the load) 0 0 1 2 3 4 5 6 7 8 9 10 RL / RS For reflection, a transmission line terminated in Zo behaves like an infinitely long transmission line Maximum power is transferred when RL = RS Network Analyzer Basics Network Analyzer Basics 2 Network Analyzer Basics Transmission Line Terminated with 25 Ω Transmission Line Terminated with Short, Open Zs = Zo Zs = Zo ZL = 25 Ω Vinc Vinc Vrefl Network Analyzer Basics Vrefl In-phase (0o) for open, out-of-phase (180o) for short For reflection, a transmission line terminated in a short or open reflects all power back to source Network Analyzer Basics High-Frequency Device Characterization Reflection Parameters Reflection Coefficient Incident Transmitted R Vreflected Γ= V incident Return loss = -20 log(ρ), B Reflected Standing wave pattern does not go to zero as with short or open A Reflected Incident = A Transmitted R Incident SWR S-Parameters S11, S22 Reflection Coefficient Γ, ρ Return Loss Impedance, Admittance R+jX, G+jB ρ Φ = ZL − ZO Z L + ZO Γ = Voltage Standing Wave Ratio Emax VSWR = Emin = 1+ρ 1-ρ B = R Group Delay Transmission Coefficient Τ,τ Full reflection (ZL = open, short) No reflection (ZL = Zo) Gain / Loss S-Parameters S21, S12 ρ Emax Emin TRANSMISSION REFLECTION = ρ 1 ∞ dB RL 0 dB 1 VSWR ∞ 0 Insertion Phase Network Analyzer Basics Network Analyzer Basics Smith Chart Review Transmission Parameters . +jX Polar plane 90 o V Incident DUT 1.0 .8 V Transmitted .6 0 +R .4 ∞→ + 180 o - o .2 0 Transmission Coefficient = ∞ 0 -jX Rectilinear impedance plane -90 V Constant X Γ= Γ= 1 V 0 ±180 ZL = Γ =1 O (open) 0 Trans Insertion Loss (dB) = - 20 Log Constant R Z L = 0 (short) = V Incident = o Z L = Zo Smith Chart maps rectilinear impedance plane onto polar plane V Transmitted Τ V O Gain (dB) = 20 Log V Smith chart Network Analyzer Basics Network Analyzer Basics 3 Trans Inc = - 20 log Inc = 20 log τ τ τ∠φ Network Analyzer Basics Criteria for Distortionless Transmission Linear Networks Linear Versus Nonlinear Behavior A * Sin 360o * f (t - to) A Linear behavior: Time to A phase shift = to * 360o * f DUT Input Frequency Magnitude f 1 Time Linear phase over bandwidth of interest Constant amplitude over bandwidth of interest Output Frequency Phase Sin 360o * f * t input and output frequencies are the same (no additional frequencies created) output frequency only undergoes magnitude and phase change Nonlinear behavior: f 1 Frequency Time f Frequency 1 output frequency may undergo frequency shift (e.g. with mixers) additional frequencies created (harmonics, intermodulation) Frequency Network Analyzer Basics Network Analyzer Basics Phase Variation with Frequency Magnitude Variation with Frequency F(t) = sin wt + 1 /3 sin 3wt + 1 /5 sin 5wt F(t) = sin wt + 1/3 sin 3wt + 1/5 sin 5wt Linear Network Time Time Time Magnitude Magnitude Linear Network Frequency Frequency 0° Frequency Frequency -360° Network Analyzer Basics Deviation from Linear Phase Group Delay Use electrical delay to remove linear portion of phase response Linear electrical length added RF filter response Frequencyω Average delay ∆φ Phase 1 /Div o yields Frequency Group delay ripple to φ Phase Deviation from linear phase o Phase 45 /Div + tg ∆ω (Electrical delay function) Low resolution Frequency -180° Frequency Network Analyzer Basics Frequency Time Frequency Group Delay (tg) = −d φ dω Frequency φ ω φ High resolution = −1 360 o * dφ df in radians/sec in degrees f in Hertz (ω = 2 π f) Network Analyzer Basics Network Analyzer Basics 4 in radians group-delay ripple indicates phase distortion average delay indicates electrical length of DUT aperture of measurement is very important Network Analyzer Basics Characterizing Unknown Devices Using parameters (H, Y, Z, S) to characterize devices: Phase Phase Why Measure Group Delay? f f −d φ dω Group Delay Group Delay −d φ dω gives linear behavioral model of our device measure parameters (e.g. voltage and current) versus frequency under various source and load conditions (e.g. short and open circuits) compute device parameters from measured data predict circuit performance under any source and load H-parameters Y-parameters Z-parameters conditions V1 = h11I1 + h12V2 I1 = y11V1 + y12V2 V1 = z11I1 + z12I2 I2 = h21I1 + h22V2 I2 = y21V1 + y22V2 V2 = z21I1 + z22I2 f f Same p-p phase ripple can result in different group delay Network Analyzer Basics V2=0 (requires short circuit) h12 = V1 V2 I1=0 (requires open circuit) Network Analyzer Basics Measuring S-Parameters Why Use S-Parameters? h11 = V1 I1 Reflected b1 b1 Transmitted S 21 = Incident a2 = 0 b1 = a 1 b Load DUT Reflected Reflected Incident b2 Transmitted 21 Z0 S 11 Forward S 11 = S Incident a1 relatively easy to obtain at high frequencies measure voltage traveling waves with a vector network analyzer don't need shorts/opens which can cause active devices to oscillate or self-destruct relate to familiar measurements (gain, loss, reflection coefficient ...) can cascade S-parameters of multiple devices to predict system performance can compute H, Y, or Z parameters from S-parameters if desired S 21 Incident Transmitted can easily import and use S-parameter files in our electronica1 b2 simulation tools S11 a2 = 0 S 22 = 2 = a 1 a2 = 0 S 12 = Reflected Incident Transmitted Incident b2 = a 2 b a1 = 0 1 = a 2 a1 = 0 DUT S22 Port 2 Reflected Port 1 a2 Incident S Transmitted 12 a1 = 0 Z0 DUT Load b1 = S11a1 + S12 a 2 b1 b 2 = S21 a1 + S22 a 2 Network Analyzer Basics Transmitted S 12 S 22 b2 Reverse Reflected a2 Incident Network Analyzer Basics Equating S-Parameters with Common Measurement Terms Criteria for Distortionless Transmission Nonlinear Networks • 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 Saturation, crossover, intermodulation, and other nonlinear effects can cause signal distortion Effect on system depends on amount and type of distortion and system architecture Time Frequency Network Analyzer Basics Network Analyzer Basics 5 Time Frequency Network Analyzer Basics What is the Difference Between Network and Spectrum Analyzers? Measuring Nonlinear Behavior 8563A LPF SPECTRUM ANALYZER . RL 0 dBm ATTEN 10 dB 10 dB / DIV Measures known signal Amplitude 8563A Amplitude Ratio Most common measurements: using a network analyzer and power sweeps gain compression AM to PM conversion using a spectrum analyzer + source(s) harmonics, particularly second and third intermodulation products resulting from two or more RF carriers SPECTRUM ANALYZER GHz 9 k Hz -2 6.5 Measures unknown signals Frequency Frequency 9 k Hz -2 6.5 GHz Network analyzers: DUT CENTER 20.00000 MHz RB 30 Hz VB 30 Hz LPF SPAN 10.00 kHz ST 20 sec Network Analyzer Basics Spectrum analyzers: measure components, devices, circuits, sub-assemblies contain source and receiver display ratioed amplitude and phase (frequency or power sweeps) offer advanced error correction measure signal amplitude characteristics carrier level, sidebands, harmonics...) can demodulate (& measure) complex signals are receivers only (single channel) can be used for scalar component test (no phase) with tracking gen. or ext. source(s) Network Analyzer Basics Agenda Generalized Network Analyzer Block Diagram Incident What measurements do we make? Network analyzer hardware Error models and calibration Example measurements Appendix Transmitted DUT SOURCE Reflected SIGNAL SEPARATION INCIDENT (R) REFLECTED (A) TRANSMITTED (B) RECEIVER / DETECTOR PROCESSOR / DISPLAY Network Analyzer Basics Network Analyzer Basics Incident Source Signal Separation Transmitted DUT Reflected SOURCE SIGNAL SEPARATION INCIDENT ( R) Supplies stimulus for system Swept frequency or power Traditionally NAs used separate source Most Agilent analyzers sold today have integrated, synthesized sources REFL ECT ED (A) TRANSMITT ED (B) RECEIVER / DETECTOR PROCESSOR / DISPLAY • • measure incident signal for reference separate incident and reflected signals splitter bridge directional coupler Network Analyzer Basics Network Analyzer Basics 6 Detector Test Port Network Analyzer Basics Interaction of Directivity with the DUT (Without Error Correction) Directivity Directivity is a measure of how well a coupler can separate signals moving in opposite directions Data Max Device (desired reflected signal) Directivity DUT RL = 40 dB Return Loss (undesired leakage signal) 0 30 Add in-phase 60 Device Frequency Directivity Directional Coupler Network Analyzer Basics Device Test port Data Min Data = Vector Sum Directivity Add out-of-phase (cancellation) Network Analyzer Basics Incident Detector Types Transmitted Broadband Diode Detection DUT Reflected SOURCE Scalar broadband (no phase information) Diode SIGNAL SEPARATION INCIDENT ( R) REFL ECT ED (A) TRANSMITT ED (B) RECEIVER / DETECTOR PROCESSOR / DISPLAY DC Easy to make broadband Inexpensive compared to tuned receiver Good for measuring frequency-translating devices Improve dynamic range by increasing power Medium sensitivity / dynamic range RF AC Tuned Receiver IF = F LO ± F RF RF ADC / DSP Vector (magnitude and phase) IF Filter LO 10 MHz Network Analyzer Basics 26.5 GHz Network Analyzer Basics Narrowband Detection - Tuned Receiver Comparison of Receiver Techniques Broadband (diode) detection ADC / DSP 0 dB Best sensitivity / dynamic range Provides harmonic / spurious signal rejection Improve dynamic range by increasing power, decreasing IF bandwidth, or averaging Trade off noise floor and measurement speed 0 dB Narrowband (tuned-receiver) detection 10 MHz -50 dB -50 dB -100 dB -100 dB -60 dBm Sensitivity higher noise floor false responses < -100 dBm Sensitivity high dynamic range harmonic immunity Dynamic range = maximum receiver power receiver noise floor 26.5 GHz Network Analyzer Basics Network Analyzer Basics 7 Network Analyzer Basics T/R Versus S-Parameter Test Sets Dynamic Range and Accuracy Source Source - 10 Transfer switch + Error (dB, deg) S-Parameter Test Set Transmission/Reflection Test Set Error Due to Interfering Signal 100 Dynamic range is very important for measurement accuracy! phase error 1 magn error 0.1 R R B A Port 1 Port 2 0.01 Fwd 0 -5 -10 -15 -20 -25 -30 -35 -40 -45 -50 -55 -60 -65 Fwd RF always comes out port 1 port 2 is always receiver response, one-port cal Network Analyzer Basics available -70 Interfering signal (dB) Network Analyzer Basics Processor / Display Incident Port 2 Port 1 DUT 0.001 B A DUT Rev RF comes out port 1 or port 2 forward and reverse measurements two-port calibration possible Internal Measurement Automation Transmitted DUT Simple: recall states More powerful: 50 MH-20GHz NETWORK ANYZER ACTIVE CHANNEL C H 2 S TA R T 775. 000 000 MH z C H 1 S TA R T 775. 000 000 MH z Reflected ENTRY S TO P 925. 000 000 MH z S TO P 925. 000 000 MH z H ld SOURCE RESPONSE PA S S 2 C or P Rm SIGNAL SEPARATION 880.435 000 M H z 1 PA S S 1 REFL ECT ED (A) STIMULUS H ld TRANSMITT ED (B) P Rm R CHANNEL INSTRUMENT STATE D uplex er T est - Tx -A nt and Ant - Rx T R L S 839.470 000 M H z CH2 CH1 S 12 S 21 log MA G log MA G 10 dB/ 10 dB/ Test sequencing 1 C or INCIDENT (R) R E F 0 dB R E F 0 dB HP-IB STATUS 1_ - 1.2468 dB 1_ - 1.9248 dB PORT 1 PORT 2 RECEIVER / DETECTOR PROCESSOR / DISPLAY CH2 START 775.000 000 MHz CH1 START 775.000 000 MHz STOP 925.000 000 MHz STOP 925.000 000 MHz Hld PASS 2 IBASIC Cor markers limit lines pass/fail indicators linear/log formats grid/polar/Smith charts PRm 880.435 000 MHz 1 available on 8753/ 8720 families keystroke recording some advanced functions ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789 + - / * = < > ( ) & "" " , . / ? ; : ' [ ] 1 ASSIGN @Hp8714 TO 800 2 OUTPUT @Hp8714;"SYST:PRES; *WAI" 3 OUTPUT @Hp8714;"ABOR;:INIT1:CONT OFF;*WAI" available on 8712 family sophisticated programs custom user interfaces 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:AUTO ONCE" 9 OUTPUT @Hp8714;"CALC1:MARK1 ON" PASS Hld 10 OUTPUT @Hp8714;"CALC1:MARK:FUNC BWID" 11 OUTPUT @Hp8714;"SENS2:STAT ON; *WAI" 1 12 OUTPUT @Hp8714;"SENS2:FUNC 'XFR:POW:RAT 1,0';DET NBAN; *WAI" 1 Cor PRm 13 OUTPUT @Hp8714;"ABOR;:INIT1:CONT OFF;:INIT1;*WAI" Duplexer Test - Tx-Ant and Ant-Rx 839.470 000 MHz CH2 CH1 S12 S21 log MAG log MAG 10 dB/ 10 dB/ REF 0 dB REF 0 dB 14 OUTPUT @Hp8714;"DISP:WIND2:TRAC:Y:AUTO ONCE" 1_ -1.2468 dB 1_ -1.9248 dB 15 OUTPUT @Hp8714;"ABOR;:INIT1:CONT ON;*WAI" 16 END Network Analyzer Basics Network Analyzer Basics Agilent’s Series of HF Vector Analyzers Agilent’s LF/RF Vector Analyzers Microwave Combination NA / SA 8510C series 8720ET/ES series 13.5, 20, 40 GHz economical fast, small, integrated test mixers, high-power amps 110 GHz in coax highest accuracy modular, flexible pulse systems Tx/Rx module test 4395A/4396B RF 8712ET/ES series 1.3, 3 GHz low cost narrowband and broadband detection IBASIC / LAN E5100A/B 8753ET/ES series 500 MHz (4395A), 1.8 GHz (4396B) impedance-measuring option fast, FFT-based spectrum analysis time-gated spectrum-analyzer option IBASIC standard test fixtures 3, 6 GHz highest RF accuracy flexible hardware more features Offset and harmonic RF sweeps LF Network Analyzer Basics Network Analyzer Basics 8 180, 300 MHz economical fast, small target markets: crystals, resonators, filters equivalent-circuit models evaporation-monitor-function option Network Analyzer Basics Agenda Spectrum Analyzer / Tracking Generator RF in IF 8563A SPECTRUM ANALYZER 9 k Hz -2 6.5 GHz LO DUT Spectrum analyzer TG out f = IF DUT Tracking generator Why do we even need error-correction and calibration? It is impossible to make perfect hardware It would be extremely expensive to make hardware good enough to eliminate the need for error correction Key differences from network analyzer: What measurements do we make? Network analyzer hardware Error models and calibration Example measurements Appendix one channel -- no ratioed or phase measurements More expensive than scalar NA (but better dynamic range) Only error correction available is normalization (and possibly open-short averaging) Poorer accuracy Small incremental cost if SA is required for other measurements Network Analyzer Basics Network Analyzer Basics Measurement Error Modeling Calibration Topics What measurements do we make? Network analyzer hardware Error models and calibration measurement errors what is vector error correction? calibration types accuracy examples calibration considerations Example measurements Appendix C AL -C RE AL Systematic errors due to imperfections in the analyzer and test setup assumed to be time invariant (predictable) 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 Errors: SYSTEMATIC Measured Data Unknown Device RANDOM DRIFT Network Analyzer Basics Network Analyzer Basics Systematic Measurement Errors Types of Error Correction R A Crosstalk Directivity response (normalization) simple to perform only corrects for tracking errors thru stores reference trace in memory, then does data divided by memory vector requires more standards requires an analyzer that can measure phase accounts for all major sources of systematic error B DUT Frequency response reflection tracking (A/R) transmission tracking (B/R) Source Mismatch Load Mismatch SHORT S11a Six forward and six reverse error terms yields 12 error terms for twoport devices Network Analyzer Basics Network Analyzer Basics 9 thru OPEN S11m LOAD Network Analyzer Basics What is Vector-Error Correction? Reflection: One-Port Model Error Adapter Ideal RF in Process of characterizing systematic error terms measure known standards remove effects from subsequent measurements 1-port calibration (reflection measurements) only 3 systematic error terms measured directivity, source match, and reflection tracking Full 2-port calibration (reflection and transmission measurements) 12 systematic error terms measured usually requires 12 measurements on four known standards (SOLT) Standards defined in cal kit definition file network analyzer contains standard cal kit definitions CAL KIT DEFINITION MUST MATCH ACTUAL CAL KIT USED! User-built standards must be characterized and entered into user cal-kit RF in 1 ED = Directivity S11A ED S11A = Actual To solve for error terms, S11A we measure 3 standards S11M = ED + to generate 3 equations 1 E S S11A ERT and 3 unknowns Assumes good termination at port two if testing two-port devices If using port 2 of NA and DUT reverse isolation is low (e.g., filter passband): assumption of good termination is not valid two-port error correction yields better results S11M = Measured ERT ES = Source Match S11M S11M Network Analyzer Basics Network Analyzer Basics Two-Port Error Correction Before and After One-Port Calibration Reverse model Forward model 0 Port 1 Port 1 EX Port 2 S21 a1 data before 1-port calibration a1 20 S 21A ES ED E RT VSWR EL' = rev load match ETT' = rev transmission tracking EX' = rev isolation 1.001 6000 12000 MHz Network Analyzer Basics A S22 b2 E S' A ED' a2 S12 A E TT' EX' E D' = rev directivity E S' = rev source match E RT' = rev reflection tracking S11 A EL = fwd load match ETT = fwd transmission tracking EX = fwd isolation b1 A a2 ED = fwd directivity E S = fwd source match ERT = fwd reflection tracking data after 1-port calibration 60 EL E L' S 12 1.1 1.01 b2 ETT S22 A S11A b1 40 Port 2 E RT' 2.0 Return Loss (dB) ERT = Reflection tracking S11A ES Each actual S-parameter is a function of all four measured S-parameters Analyzer must make forward and reverse sweep to update any one Sparameter Luckily, you don't need to know these equations to use network analyzers!!! S 22a = E RT E RT ' E TT ETT ' (1 + 11m E S )(1 + 22 m E S ' ) − E L ' E L ( 21m )( ) S S − ED' S − E X S12 m − E X ' − ED E RT ' E RT ETT E TT ' ( 22m )( 1 + 11m E S ) − E L ' ( 21m )( 12m ) D D X S −E ' S −E S −E S − EX ' S12a = E RT E RT ' E TT E TT ' (1 + 11m E S )(1 + 22 m E S ' ) − E L ' E L ( 21m )( ) S − ED S − ED' S − E X S12 m − E X ' E TT ' E RT S L ( 12m )(1 + 11m ( E − E ' )) S − EX ' S − ED S21a = E RT E RT ' E TT E TT ' (1 + 11m E S )(1 + 22 m E S ' ) − E L ' E L ( 21m )( ) − ED − ED' − E X S12 m − E X ' S S S E TT E RT ' ( )(1 + ( E S ' − E L )) S21m − E X S22 m − E D ' S11a = E RT E RT ' E TT ETT ' (1 + 11m E S )(1 + 22 m E S ' ) − E L ' E L ( 21m )( ) S − E D' S − ED ' S − E X S12 m − E X ' E RT E RT ' E TT E TT ' S ') − EL( ( 11m )( 1 + E )( ) S − ED S 22 m − E D ' S 21m − E X S12 m − E X ' Network Analyzer Basics Crosstalk: Signal Leakage Between Test Ports During Transmission Errors and Calibration Standards DUT UNCORRECTED FULL 2-PORT Can be a problem with: high-isolation devices (e.g., switch in open position) high-dynamic range devices (some filter stopbands) Isolation calibration adds noise to error model (measuring near noise floor of system) only perform if really needed (use averaging if necessary) if crosstalk is independent of DUT match, use two terminations if dependent on DUT match, use DUT with termination on output RESPONSE DUT OPEN thru Convenient Generally not accurate No errors removed LOAD Easy to perform Use when highest accuracy is not required Removes frequency response error ENHANCED-RESPONSE DUT LOAD Network Analyzer Basics Combines response and 1-port Corrects source match for transmission measurements Network Analyzer Basics 10 SHORT OPEN OPEN LOAD LOAD DUT DUT SHORT DUT LOAD 1-PORT SHORT For reflection measurements Need good termination for high accuracy with twoport devices Removes these errors: Directivity Source match Reflection tracking thru DUT Highest accuracy Removes these errors: Directivity Source, load match Reflection tracking Transmission tracking Crosstalk Network Analyzer Basics Calibration Summary Reflection Test Set (cal type) T/R Reflection tracking Directivity Source match Load match SHORT Remember: convert all dB values to linear for uncertainty calculations! S-parameter (one-port) Reflection Example Using a One-Port Cal (two-port) OPEN Directivity: 40 dB (.010) T/R DUT S-parameter (two-port) (response, isolation) .158 error can be corrected Transmission Tracking Crosstalk Source match ( Load match error cannot be corrected enhanced response cal corrects for source match during transmission measurements * -20 * log (.158 - .100 - .010) = 26.4 dB (+10.4 dB) Network Analyzer Basics Using a One-Port Cal + Attenuator Load match: 18 dB (.126) 10 dB attenuator (.316) SWR = 1.05 (.024) Transmission Example Using Response Cal Measurement uncertainty: -20 * log (.158 + .039) = 14.1 dB (-1.9 dB) -20 * log (.158 - .039) = 18.5 dB (+2.5 dB) RL = 18 dB (.126) RL = 14 dB (.200) Thru calibration (normalization) builds error into measurement due to source and load match interaction DUT 16 dB RL (.158) 1 dB loss (.891) .158 Calibration Uncertainty = (1 ± ρS ρL) Low-loss bi-directional devices generally require two-port calibration Worst-case error = .010 + .010 + .019 = .039 for low measurement uncertainty (.891)(.316)(.126)(.316)(.891) = .010 (.891)(.024)(.891) = .019 = (1 ± (.200)(.126) = ± 0.22 dB Network Analyzer Basics Network Analyzer Basics Filter Measurement with Response Cal Source match = 14 dB (.200) Measurement uncertainty: -20 * log (.158 + .100 + .010) = 11.4 dB (-4.6dB) (.891)(.126)(.891) = .100 * ) Network Analyzer Basics Directivity: 40 dB (.010) 20 16 dB RL (.158) 1 dB loss (.891) Test Set (cal type) Transmission ρ or loss(linear) = 10 -dB ( ) Load match: 18 dB (.126) LOAD DUT 1 dB loss (.891) 16 dB RL (.158) Measuring Amplifiers with a Response Cal Load match = 18 dB (.126) 1 Source match = 14 dB (.200) DUT 16 dB RL (.158) Load match = 18 dB (.126) 1 (.126)(.158) = .020 (.126)(.158) = .020 (.126)(.891)(.200)(.891) = .020 (.158)(.200) = .032 (.158)(.200) = .032 Total measurement uncertainty: +0.60 + 0.22 = + 0.82 dB -0.65 - 0.22 = - 0.87 dB Total measurement uncertainty: +0.44 + 0.22 = + 0.66 dB -0.46 - 0.22 = - 0.68 dB Measurement uncertainty = 1 ± (.020+.020+.032) = 1 ± .072 = + 0.60 dB - 0.65 dB Network Analyzer Basics Network Analyzer Basics 11 Measurement uncertainty = 1 ± (.020+.032) = 1 ± .052 = + 0.44 dB - 0.46 dB Network Analyzer Basics Filter Measurements using the Enhanced Response Calibration Effective source match = 35 dB! DUT 1 dB loss (.891) 16 dB RL (.158) Source match = 35 dB (.0178) Load match = 18 dB (.126) Using the Enhanced Response Calibration Plus an Attenuator Calibration Uncertainty = (1 ± ρS ρL) 10 dB attenuator (.316) SWR = 1.05 (.024 linear or 32.4 dB) Analyzer load match =18 dB (.126) Calibration Uncertainty = (1 ± ρS ρL) = (1 ± (.0178)(.126) = ± .02 dB DUT 1 dB loss (.891) 16 dB RL (.158) Source match = 35 dB (.0178) 1 Measurement uncertainty = 1 ± (.020+.0018+.0028) (.126)(.158) = .020 = 1 ± .0246 = + 0.211 dB (.126)(.891)(.0178)(.891) = .0018 - 0.216 dB = (1 ± (.0178)(.0366) = ± .01 dB Effective load match = (.316)(.316)(.126) + .024 = .0366 (28.7dB) 1 Measurement uncertainty = 1 ± (.006+.0005+.0028) = 1 ± .0093 (.0366)(.891)(.0178)(.891) = .0005 = ± 0.08 dB (.0366)(.158) = .006 (.158)(.0178) = .0028 (.158)(.0178) = .0028 Total measurement uncertainty: 0.22 + .02 = ± 0.24 dB Total measurement uncertainty: 0.01 + .08 = ± 0.09 dB Network Analyzer Basics Network Analyzer Basics Calculating Measurement Uncertainty After a Two-Port Calibration DUT 1 dB loss (.891) 16 dB RL (.158) Corrected error terms: (8753ES 1.3-3 GHz Type-N) Directivity Source match Load match Refl. tracking Trans. tracking Isolation = 47 dB = 36 dB = 47 dB = .019 dB = .026 dB = 100 dB Response versus Two-Port Calibration Measuring filter insertion loss CH1 S21&M log MAG CH2 MEM log MAG Reflection uncertainty 1 dB/ 1 dB/ REF 0 dB REF 0 dB Cor After two-port calibration S11m = S11a ± ( ED + S11a 2 ES + S21a S12a EL + S11a (1 − ERT )) = 0158 . ± (.0045 + 0158 . 2 *.0158 + 0891 . 2 *.0045 + 0158 . *.0022) After response calibration = 0.158 ± .0088 = 16 dB +0.53 dB, -0.44 dB (worst-case) Transmission uncertainty S21m = S21a ± S21a ( E I / S21a + S11a E S + S21a S12a E S E L + S22a E L + (1 − ETT )) = 0891 . ± 0891 . (10−6 / 0.891 + 0158 . *.0158 + 0.8912 *.0158*.0045 + 0158 . *.0045+.003) x2 1 = 0.891 ± .0056 = 1 dB ±0.05 dB (worst-case) Network Analyzer Basics • • 2 STOP 6 000.000 MHz START 2 000.000 MHz Network Analyzer Basics ECal: Electronic Calibration (85060/90 series) • Uncorrected Cor Variety of modules cover 30 kHz to 26.5 GHz Six connector types available (50 Ω and 75 Ω) Single-connection reduces calibration time makes calibrations easy to perform minimizes wear on cables and standards eliminates operator errors Highly repeatable temperature-compensated terminations provide excellent accuracy Adapter Considerations reflection from adapter leakage signal desired signal ρ measured = Directivity + ρ adapter + ρ DUT Coupler directivity = 40 dB 85093A Electronic Calibration Module 30 kHz - 6 GHz Adapter DUT Termination DUT has SMA (f) connectors Worst-case System Directivity • 28 dB Microwave modules use a transmission line shunted by PIN-diode switches in various combinations 17 dB 14 dB Network Analyzer Basics Network Analyzer Basics 12 APC-7 calibration done here Adapting from APC-7 to SMA (m) APC-7 to SMA (m) SWR:1.06 APC-7 to N (f) + N (m) to SMA (m) SWR:1.05 SWR:1.25 APC-7 to N (m) + N (f) to SMA (f) + SMA (m) to (m) SWR:1.05 SWR:1.25 SWR:1.15 Network Analyzer Basics Calibrating Non-Insertable Devices Swap Equal Adapters Method When doing a through cal, normally test ports mate directly cables can be connected directly without an adapter result is a zero-length through What is an insertable device? has same type of connector, but different sex on each port has same type of sexless connector on each port (e.g. APC-7) What is a non-insertable device? one that cannot be inserted in place of a zero-length through has same connectors on each port (type and sex) has different type of connector on each port (e.g., DUT waveguide on one port, coaxial on the other) What calibration choices do I have for non-insertable devices? use an uncharacterized through adapter use a characterized through adapter (modify cal-kit definition) swap equal adapters adapter removal Port 1 Port 1 Port 1 Port 1 Network Analyzer Basics Port 1 Calibration is very accurate and traceable In firmware of 8753, 8720 and 8510 series Also accomplished with ECal modules (85060/90) Uses adapter with same connectors as DUT Must specify electrical length of adapter to within 1/4 wavelength of highest frequency (to avoid phase ambiguity) Cal Adapter Port 1 Cal Adapter Adapter B Port 2 Adapter B Port 2 DUT Port 2 2. Reflection cal using adapter B. Adapter B Port 2 3. Measure DUT using adapter B. We know about Short-Open-Load-Thru (SOLT) calibration... What is TRL? A two-port calibration technique Good for noncoaxial environments (waveguide, fixtures, wafer probing) Uses the same 12-term error model as the more common SOLT cal Uses practical calibration standards that are easily fabricated and characterized Two variations: TRL (requires 4 receivers) and TRL* (only three receivers needed) Other variations: Line-Reflect-Match (LRM), Thru-Reflect-Match (TRM), plus many others TRL was developed for non-coaxial microwave measurements Port 2 1. Perform 2-port cal with adapter on port 2. Save in cal set 1. 2. Perform 2-port cal with adapter on port 1. Save in cal set 2. Cal Set 2 [CAL] [MORE] [MODIFY CAL SET] [ADAPTER REMOVAL] Port 1 Adapter B Thru-Reflect-Line (TRL) Calibration Cal Set 1 Port 1 DUT 1. Transmission cal using adapter A. Port 2 Network Analyzer Basics Adapter Removal Calibration Adapter A Accuracy depends on how well the adapters are matched - loss, electrical length, match and impedance should all be equal Port 2 DUT DUT Adapter B Port 2 3. Use ADAPTER REMOVAL to generate new cal set. 4. Measure DUT without cal adapter. Network Analyzer Basics Network Analyzer Basics Frequency Sweep - Filter Test Agenda CH1 S21 log MAG 10 dB/ REF 0 dB CH1 S11 log MAG 5 dB/ REF 0 dB Cor What measurements do we make? Network analyzer hardware Error models and calibration Example measurements Appendix Stopba nd rejectio n 69.1 dB START .300 000 MHz STOP 400.000 000 MHz CH1 S21 SPAN 50.000 MHz CENTER 200.000 MHz log MAG 1 dB/ REF 0 dB Return loss Cor 1 m1: 4.000 000 GHz 0.16 dB m2-ref: 2.145 234 GHz 0.00 dB ref 2 Cor Insertion loss x2 1 START 2 000.000 MHz Network Analyzer Basics Network Analyzer Basics 13 2 STOP 6 000.000 MHz Network Analyzer Basics Optimize Filter Measurements with Swept-List Mode Power Sweeps - Compression Segment 3: 29 ms (108 points, -10 dBm, 6000 Hz) CH1 S 21 log MAG 12 dB/ REF 0 dB PRm PASS Segment 5: 129 ms (38 points, +10 dBm, 300 Hz) Segment 1: 87 ms (25 points, +10 dBm, 300 Hz) Saturated output power Output Power (dBm) Swept-list sweep: 349 ms (201 pts, variable BW's & power) Linear sweep: 676 ms (201 pts, 300 Hz, -10 dBm) Compression region Linear region (slope = small-signal gain) START 525.000 000 MHz STOP 1 275.000 000 MHz Input Power (dBm) Segments 2,4: 52 ms (15 points, +10 dBm, 300 Hz) Network Analyzer Basics Network Analyzer Basics AM to PM Conversion Power Sweep - Gain Compression CH1 S21 1og MAG 1 dB/ REF 32 dB 30.991 dB 12.3 dBm Amplitude Measure of phase deviation caused by amplitude Power sweep variations AM (dB) Mag(Am i n) DUT 1 dB compression: PM (deg) input power resulting in 1 dB drop in gain 1 0 Test Stimulus Q Time Amplitude AM (dB) START -10 dBm CW 902.7 MHz AM - PM Conversion = Mag(Pm (deg/d ) Mag(Am out B) in) STOP 15 dBm Mag(AMo ut) PM (deg) Mag(Pm o ut) Time Output Response Network Analyzer Basics Log Mag /M Phase Agenda 1.0 dB/ 5.0 deg/ Ch1:Mkr1 20.48 dB Ch2:Mkr2 0.86 deg Ref -115.7 deg Ref 21.50 dB -4.50 dBm What measurements do we make? Network analyzer hardware Error models and calibration Example measurements Appendix 1.00 dB 2 1 Use transmission setup with a power sweep Display phase of S21 AM - PM = 0.86 deg/dB 2 1 1 Start -10.00 dBm Start -10.00 dBm I AM to PM conversion can cause bit errors Network Analyzer Basics Measuring AM to PM Conversion 1:Transmission 2:Transmission AM can be undesired: supply ripple, fading, thermal AM can be desired: modulation (e.g. QAM) CW 900.000 MHz CW 900.000 MHz Stop 0.00 dBm Stop 0.00 dBm Network Analyzer Basics Network Analyzer Basics 14 Advanced Topics time domain frequency-translating devices high-power amplifiers extended dynamic range multiport devices in-fixture measurements crystal resonators balanced/differential Inside the network analyzer Challenge quiz! Network Analyzer Basics TDR Basics Using a Network Analyzer Time-Domain Reflectometry (TDR) What is TDR? time-domain reflectometry analyze impedance versus time distinguish between inductive and capacitive transitions With gating: analyze transitions inductive analyzer standards transition start with broadband frequency sweep (often requires microwave VNA) use inverse-Fourier transform to compute time-domain resolution inversely proportionate to frequency span Time Domain Frequency Domain F CH1 S 22 -1 Re Cor 50 mU/ REF 0 U 20 GHz f t 6 GHz impedance t ∫ F(t)*dt Integrate 0 time capacitive transition TDR F Network Analyzer Basics Cor 2 REF 0 U 1: -45.113 dB 0.947 GHz 2: -15.78 dB 6.000 GHz Gate 1: 48.729 mU 638 ps RISE TIME 29.994 ps 8.992 mm STOP 1.5 ns 1. Set up desired frequency range (need wide span for good spatial resolution) 2. Under SYSTEM, transform menu, press "set freq low pass" 3. Perform one- or two-port calibration 4. 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 desired 9. For gating: set start and stop frequencies for gate turn gating on * adjust gate shape to trade off resolution with ripple * 10. To display gated response in frequency domain turn transform off (leave gating on) * change format to log-magnitude * PRm 20 mU/ CH1 START 0 s Ten Steps for Performing TDR TDR and gating can remove undesired reflections (a form of error correction) Only useful for broadband devices (a load or thru for example) Define gate to only include DUT CH1 S11&M log MAG 5 dB/ REF 0 dB Use two-port calibration CH1 MEM Re f Network Analyzer Basics Time-Domain Gating -1 non-Zo transmission line t PRm Cor 1/s*F(s) Zo 2: 24.961 mU 668 ps 1 3: -10.891 mU 721 ps 2 3 Thru in time domain CH1 START 0 s Thru in frequency domain, with and without gating 1 STOP 1.5 ns START .050 000 000 GHz * If using two channels (even if coupled), these parameters must be set independently for second channel STOP 20.050 000 000 GHz Network Analyzer Basics Network Analyzer Basics Time-Domain Transmission Time-Domain Filter Tuning RF Input • RF Output CH1 S21 log MAG Main Wave Leakage log MAG • Surface Wave Triple Travel CH1 S21 15 dB/ REF 0 dB 10 dB/ REF 0 dB Cor Cor RF Leakage Triple Travel • Gate off Gate on START -1 us Deterministic method used for tuning cavity-resonator filters Traditional frequency-domain tuning is very difficult: lots of training needed may take 20 to 90 minutes to tune a single filter Need VNA with fast sweep speeds and fast time-domain processing STOP 6 us Network Analyzer Basics Network Analyzer Basics 15 Network Analyzer Basics Filter Reflection in Time Domain Tuning Resonator #3 • • • • • Set analyzer’s center frequency = center frequency of the filter Measure S11 or S22 in the time domain Nulls in the time-domain response correspond to individual resonators in filter • • Network Analyzer Basics Easier to identify mistuned resonator in time-domain: null #3 is missing Hard to tell which resonator is mistuned from frequency-domain response Adjust resonators by minimizing null Adjust coupling apertures using the peaks in-between the dips Network Analyzer Basics Frequency-Translating Devices Medium-dynamic range measurements (35 dB) High-Power Amplifiers High-dynamic range measurements (100 dB) Preamp 8753ES FREQ OFFS ON off 8753ES 8753ES Source LO MENU Ref In Ref In 1 2 DOW N CONVERTER Filter Ref out UP CONVERTER Attenuator Attenuator Ref in RF > LO Preamp Reference mixer AUT DUT R RF < LO Start: 900 MHz Start: 100 MHz Stop: 350 MHz Stop: 650 MHz LO power: 13 dBm CH1 CONV MEAS Filter VIEW MEASURE Fixed LO: 1 GHz B A Attenuator RETURN log MAG 10 dB/ DUT REF 10 dB Attenuator AUT Attenuat or +43 dBm max input (20 watts!) 8720ES Option 085 ESG-D4000A START 640.000 000 MHz Powe r splitt er 85118A High-Power Amplifier Test System STOP 660.000 000 MHz Network Analyzer Basics Network Analyzer Basics High-Dynamic Range Measurements CH1 MEM CH2 MEM LOG LOG 15 dB/ 15 dB/ REF 3 dB REF 3 dB Multiport Device Test • • PRm Cor Avg 10 8753 H39 CH1 CH2 PRm S21 S12 log MA G log MA G 10 dB/ 10 dB/ REF 0 dB REF 0 dB 1_ -1.9248 dB 1_ -1.2468 dB 839.470 000 MHz PRm Duplexer Test - Tx-Ant and Ant-Rx Cor 1 Standard 8753ES 1 Hld PASS 1 Cor Avg 10 880.435 000 MHz PRm Cor 2 • 8753ES Special Option H16 CH1 CH2 START 775. 000 000 MHz START 775. 000 000 MHz PASS Hld CH1 STA RT 775.000 000 MHz CH2 STA RT 775.000 000 MHz STOP 1000. 000 000 MHz STOP 1000. 000 000 MHz Network Analyzer Basics Network Analyzer Basics 16 STOP 925.000 000 MHz STOP 925.000 000 MHz Multiport analyzers and test sets: improve throughput by reducing the number of connections to DUTs with more than two ports allow simultaneous viewing of two paths (good for tuning duplexers) include mechanical or solid-state switches, 50 or 75 ohms degrade raw performance so calibration is a must (use two-port cals whenever possible) Agilent offers a variety of standard and custom multiport analyzers and test sets Network Analyzer Basics Test Set Cal Eliminates Redundant Connections of Calibration Standards SelfCal Once a month: perform a Test Set Cal with external standards to remove systematic errors in the analyzer, test set, cables, and fixture Test Set Cal 87050E/87075C Standard Multiport Test Sets Through Connections Reflection Connections 12-port 12-port 8-port 8-port 4-port 4-port Fixture DUT • • • • • Once an hour: For use with 8712E family automatically perform a SelfCal using internal standards to 50 Ω: 3 MHz to 2.2 GHz, 4, 8, or 12 ports remove systematic errors in the analyzer and test set 75 Ω: 3 MHz to 1.3 GHz, 6 or 12 ports Test Set Cal and SelfCal dramatically improve calibration times Systems offer fully-specified performance at test ports 0 Network Analyzer Basics 100 200 300 400 0 25 50 Test Set Cal Traditional VNA Calibration 75 Network Analyzer Basics In-Fixture Measurements Characterizing Crystal Resonators/Filters Measurement problem: coaxial calibration plane is not the same as the in-fixture measurement plane E5100A/B Network Analyzer Ch1 Z: R phase 40 / REF 0 1: 15.621 U 31.998 984 925 MHz Min Cor Measurement plane Calibration plane Fixture 1 ED ES DUT ET Error correction with coaxial calibration STA RT 31.995 MHz SEG START POINTS STOP 32.058 MHz POWER IFBW 32.008 MHz 200 0 dBm 200Hz > 2 32.052 MHz 32.058 MHz 200 0 dBm 200Hz END Loss Phase shift Mismatch Example of crystal resonator measurement Network Analyzer Basics Network Analyzer Basics Balanced-Device Measurements • STOP 1 31.995 MHz Traditional Scalar Analyzer Incident ATN-4000 series (4-port test set + software) Transmitted DUT Reflected • • • • • • SOURCE measure tough singled-ended devices like couplers measure fully-balanced or single-ended-to-balanced DUTs characterize mode conversions (e.g. common-to-differential) incorporates 4-port error correction for exceptional accuracy works with 8753ES and 8720ES analyzers more info at www.atnmicrowave.com SIGNAL SEPARATION processor/display INCIDENT ( R) REFL ECT ED (A) TRANSMITT ED (B) RECEIVER / DETECTOR source PROCESSOR / DISPLAY Example: 8757D/E requires external detectors, couplers, bridges, splitters good for low-cost microwave scalar applications RF R A B RF Detector R Detector Detector Bridge Channel Partner Reflection Network Analyzer Basics Network Analyzer Basics 17 DUT DUT Termination Transmission A B Network Analyzer Basics One Method of Measuring Coupler Directivity Directional Coupler Directivity Coupling Factor (fwd) x Loss (through arm) Directivity = 1.0 (0 dB) (reference) Isolation (rev) Directivity (dB) = Isolation (dB) - Coupling Factor (dB) - Loss (dB) 50 dB Test port 50 dB Coupler 35 dB (.018) Directivity Examples: 20 dB Source Directivity = 50 dB - 20 dB = 30 dB 30 dB short .018 (35 dB) (normalized) Test port Directivity = 35 dB - 0 dB Directivity = 50 dB - 30 dB - 10 dB = 10 dB = 35 dB 10 dB 60 dB 20 dB Test port Directivity = 60 dB - 20 dB - 10 dB = 30 dB load Source 10 dB Network Analyzer Basics Network Analyzer Basics 50 Ω 50 Ω Detector 50 Ω 50-ohm load at test port balances the bridge -- detector reads zero Non-50-ohm load imbalances bridge Measuring magnitude and phase of imbalance gives complex impedance "Directivity" is difference between maximum and minimum balance ADC / DSP TRANSMITT ED (B) Mixer-based front end It is cheaper and easier to make broadband front ends using samplers instead of mixers Harmonic generator f frequency "comb" Network Analyzer Basics Why Are Four Receivers Better Than Three? TRL R1 R A B B Port 2 3 receivers more economical TRL*, LRM* cals only includes: 8753ES 8720ES (standard) Port 2 Port 1 4 receivers TRL* assumes the source and load match of a test port are equal (port symmetry between forward and reverse measurements) this is only a fair assumption for three-receiver network analyzers TRL four receivers are necessary to make the required measurements TRL and TRL* use identical calibration standards In noncoaxial applications, TRL achieves better source and load match correction than TRL* What about coaxial applications? SOLT is usually the preferred calibration method coaxial TRL can be more accurate than SOLT, but not commonly used R2 Port 1 TRL* 8720ES Option 400 adds fourth sampler, allowing full TRL calibration Transfer switch Transfer switch REFL ECT ED (A) ADC / DSP S Source SIGNAL SEPARATION INCIDENT ( R) PROCESSOR / DISPLAY Test Port Source SOURCE Sampler-based front end Three Versus Four-Receiver Analyzers Transmitted DUT Reflected RECEIVER / DETECTOR Network Analyzer Basics Incident NA Hardware: Front Ends, Mixers Versus Samplers Directional Bridge A Assume perfect load (no reflection) more expensive true TRL, LRM cals includes: 8720ES (option 400) 8510C Network Analyzer Basics Network Analyzer Basics 18 Network Analyzer Basics Challenge Quiz Challenge Quiz (continued) 1. Can filters cause distortion in communications systems? A. Yes, due to impairment of phase and magnitude response B. Yes, due to nonlinear components such as ferrite inductors C. No, only active devices can cause distortion D. No, filters only cause linear phase shifts E. Both A and B above 4. Maximum dynamic range with narrowband detection is defined as: A. Maximum receiver input power minus the stopband of the device under test B. Maximum receiver input power minus the receiver's noise floor C. Detector 1-dB-compression point minus the harmonic level of the source D. Receiver damage level plus the maximum source output power E. Maximum source output power minus the receiver's noise floor 2. Which statement about transmission lines is false? A. Useful for efficient transmission of RF power B. Requires termination in characteristic impedance for low VSWR C. Envelope voltage of RF signal is independent of position along line D. Used when wavelength of signal is small compared to length of line E. Can be realized in a variety of forms such as coaxial, waveguide, microstrip 5. With a T/R analyzer, the following error terms can be corrected: A. Source match, load match, transmission tracking B. Load match, reflection tracking, transmission tracking C. Source match, reflection tracking, transmission tracking D. Directivity, source match, load match E. Directivity, reflection tracking, load match 3. Which statement about narrowband detection is false? A. Is generally the cheapest way to detect microwave signals B. Provides much greater dynamic range than diode detection C. Uses variable-bandwidth IF filters to set analyzer noise floor D. Provides rejection of harmonic and spurious signals E. Uses mixers or samplers as downconverters 6. Calibration(s) can remove which of the following types of measurement error? A. Systematic and drift B. Systematic and random C. Random and drift D. Repeatability and systematic E. Repeatability and drift Network Analyzer Basics Network Analyzer Basics Answers to Challenge Quiz Challenge Quiz (continued) 7. Which statement about TRL calibration is false? A. Is a type of two-port error correction B. Uses easily fabricated and characterized standards C. Most commonly used in noncoaxial environments D. Is not available on the 8720ES family of microwave network analyzers E. Has a special version for three-sampler network analyzers 1. E 2. C 3. A 4. B 5. C 6. A 7. D 8. B 9. E 8. 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 compression B. Cables because load match cannot be corrected C. Filter stopbands because of lack of dynamic range D. Mixers because of lack of broadband detectors E. Attenuators because source match cannot be corrected 9. Power sweeps are good for which measurements? A. Gain compression B. AM to PM conversion C. Saturated output power D. Power linearity E. All of the above Network Analyzer Basics Network Analyzer Basics 19