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
Telecommunications engineering wikipedia , lookup
Alternating current wikipedia , lookup
History of electric power transmission wikipedia , lookup
Utility frequency wikipedia , lookup
Transmission line loudspeaker wikipedia , lookup
Chirp spectrum wikipedia , lookup
Two-port network wikipedia , lookup
Rectiverter wikipedia , lookup
Distribution management system wikipedia , lookup
Network Analyzer Basics Network Analyzer Basics Copyright 2000 Network Analysis is NOT.… R o u t e r B r i d g e R e p e a t e r H u b Y o u r I E E E 8 0 2 . 3 X . 2 5 I S D N s w i t c h e d p a c k e td a t a s t r e a m i s r u n n i n g a t1 4 7 M B P S w i t h 9 a B E R o f1 . 5 2 3 X 1 0... Network Analyzer Basics Copyright 2000 Low Integration High What Types of Devices are Tested? Duplexers Diplexers Filters Couplers Bridges Splitters, dividers Combiners Isolators Circulators Attenuators Adapters Opens, shorts, loads Delay lines Cables Transmission lines Waveguide Resonators Dielectrics R, L, C's Passive Network Analyzer Basics RFICs MMICs T/R modules Transceivers Receivers Tuners Converters VCAs Amplifiers Antennas Switches Multiplexers Mixers Samplers Multipliers Diodes Device type VCOs VTFs Oscillators Modulators VCAtten’s Transistors Active Copyright 2000 Complex Device Test Measurement Model 84000 RFIC test Ded. Testers VSA Response tool SA Harm. Dist. LO stability Image Rej. VNA SNA NF Mtr. NF Imped. An. LCR/Z I-V Measurement plane Absol. Power Gain/Flatness Power Mtr. Simpl e Full call sequence Pulsed S-parm. Pulse profiling Gain/Flat. Compr'n Phase/GD AM-PM Isolation Rtn Ls/VSWR Impedance S-parameters TG/SA Param. An. Intermodulation Distortion NF BER EVM ACP Regrowth Constell. Eye Det/Scope DC CW Swept Swept freq power modulation RF Simple Network Analyzer Basics Noise 2-tone Multi- Stimulus type Complex tone Pulsed- Protocol Complex Copyright 2000 Lightwave Analogy to RF Energy Incident Reflected Transmitted Lightwave DUT RF Network Analyzer Basics Copyright 2000 Why Do We Need to Test Components? • 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, AMto-PM conversion • Ensure good match when absorbing power (e.g., an antenna) F M 9 7 K P W R Network Analyzer Basics Copyright 2000 The Need for Both Magnitude and Phase 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 Emitter Network Analyzer Basics Measured Actual Copyright 2000 Transmission Line Basics + I - 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 High frequencies wavelength or << length of transmission medium need transmission lines for efficient power transmission matching to characteristic impedance (Zo) is very important for low reflection and maximum Network Analyzer Basics power transfer Copyright 2000 Transmission line Zo • • Zo determines relationship between voltage and current waves Zo is a function of physical dimensions and r Zo is usually a real impedance (e.g. 50 or 75 ohms) 1.5 attenuation is lowest at 77 ohms 1.4 1.3 1.2 normalized values • 1.1 50 ohm standard 1.0 0.9 0.8 0.7 power handling capacity peaks at 30 ohms 0.6 0.5 10 20 30 40 50 60 70 80 90 100 characteristic impedance for coaxial airlines (ohms) Network Analyzer Basics Copyright 2000 Power Transfer Efficiency RS For complex impedances, maximum power transfer occurs when ZL = ZS* (conjugate match) RL R s + j X Load Power (normalized) 1.2 1 j X 0.8 0.6 R L 0.4 0.2 0 0 1 2 3 4 5 6 7 8 9 10 RL / RS Maximum power is transferred when RL = RS Network Analyzer Basics Copyright 2000 Transmission Line Terminated with Zo Zs = Zo Zo = characteristic impedance of transmission line Zo Vinc Vrefl = 0! (all the incident power is absorbed in the load) For reflection, a transmission line terminated in Zo behaves like an infinitely long transmission line Network Analyzer Basics Copyright 2000 Transmission Line Terminated with Short, Open Zs = Zo Vinc Vrefl Network Analyzer Basics 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 Copyright 2000 Transmission Line Terminated with 25 W Zs = Zo ZL = 25 W Vinc Vrefl Network Analyzer Basics Standing wave pattern does not go to zero as with short or open Copyright 2000 High-Frequency Device Characterization Incident Transmitted R B Reflected A TRANSMISSION REFLECTION Reflected Incident = SWR S-Parameters S11, S22 Reflection Coefficient G, r Network Analyzer Basics A Transmitted R Incident Return Loss Impedance, Admittance R+jX, G+jB = B R Group Delay Gain / Loss S-Parameters S21, S12 Transmission Coefficient T,t Insertion Phase Copyright 2000 Reflection Parameters Reflection Coefficient G Vreflected = = Vincident Return loss = -20 log(r), r r F = ZL - ZO Z L + ZO G = Emax Emin Voltage Standing Wave Ratio Emax VSWR = Emin = 1+r 1-r Full reflection (ZL = open, short) No reflection (ZL = Zo) 0 r 1 dB RL 0 dB 1 VSWR Network Analyzer Basics Copyright 2000 Smith Chart Review . +jX Polar plane 90 o 1.0 .8 .6 0 +R .4 + 180 o - o .2 0 0 -jX -90 o Rectilinear impedance plane Constant X Constant R Z L = Zo Smith Chart maps rectilinear impedance plane onto polar plane Network Analyzer Basics G= 0 G= 1 ±180 (open) ZL = Z L = 0 (short) G =1 O 0 Smith chart Copyright 2000 O Transmission Parameters V Incident DUT Transmission Coefficient = T V = Trans Insertion Loss (dB) = - 20 Log V V Gain (dB) = 20 Log V Network Analyzer Basics Trans V Transmitted V Transmitted V Incident = - 20 log = t t Inc = 20 log t Inc Copyright 2000 Linear Versus Nonlinear Behavior A * Sin 360o * f (t - to) A Linear behavior: Time to Sin 360o * f * t A Time f 1 DUT Input phase shift = to * 360o * f input and output frequencies are the same (no additional frequencies created) output frequency only undergoes magnitude and phase change Frequency Output Nonlinear behavior: f 1 Frequency Time f Network Analyzer Basics 1 Frequency output frequency may undergo frequency shift (e.g. with mixers) additional frequencies created (harmonics, intermodulation) Copyright 2000 Criteria for Distortionless Transmission Linear Networks Linear phase over bandwidth of interest Magnitude Constant amplitude over bandwidth of interest Phase Frequency Frequency Network Analyzer Basics Copyright 2000 Magnitude Variation with Frequency F(t) = sin wt + 1/3 sin 3wt + 1/5 sin 5wt Time Time Magnitude Linear Network Frequency Network Analyzer Basics Frequency Frequency Copyright 2000 Phase Variation with Frequency F(t) = sin wt + 1 /3 sin 3wt + 1 /5 sin 5wt Linear Network Time Magnitude Time Frequency 0° Frequency -180° Frequency -360 ° Network Analyzer Basics Copyright 2000 Deviation from Linear Phase Use electrical delay to remove linear portion of phase response Linear electrical length added Phase 45 /Div RF filter response Deviation from linear phase o o Phase 1 /Div (Electrical delay function) + Frequency Low resolution Network Analyzer Basics yields Frequency Frequency High resolution Copyright 2000 Group Delay Frequencyw tg Group delay ripple Dw to Phase Average delay D Frequency Group Delay (tg) = -d dw w = -1 360 o * d df in radians in radians/sec group-delay ripple indicates phase distortion average delay indicates electrical length of DUT aperture of measurement is very important in degrees f in Hertz (w = 2 p f) Network Analyzer Basics Copyright 2000 Phase Phase Why Measure Group Delay? f f -d dw Group Delay Group Delay -d dw f f Same p-p phase ripple can result in different group delay Network Analyzer Basics Copyright 2000 Characterizing Unknown Devices Using parameters (H, Y, Z, S) to characterize devices: 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 Network Analyzer Basics I2 = y21V1 + y22V2 V2 = z21I1 + z22I2 h11 = V1 I1 V2=0 (requires short circuit) h12 = V1 V2 I1=0 (requires open circuit) Copyright 2000 Why Use S-Parameters? 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 can easily import and use S-parameter files in our electronicsimulation tools a1 S 21 Incident b2 S11 Reflected b1 Transmitted DUT Port 1 Transmitted Port 2 S12 S22 Reflected a2 Incident b1 = S11 a1 + S12 a 2 b 2 = S21 a1 + S22 a 2 Network Analyzer Basics Copyright 2000 Measuring S-Parameters a1 Forward S 21 = b1 Incident a2 = 0 b1 = a 1 b a2 = 0 Z0 a2 = 0 DUT Load Network Analyzer Basics S 22 = 2 = a 1 a1 = 0 b1 Load DUT Reflected Transmitted b2 Transmitted 21 Z0 S 11 Reflected Incident S 11 = S Incident Transmitted S 12 S 12 = Reflected Incident Transmitted Incident S 22 b2 = a 2 b a1 = 0 1 = a 2 a1 = 0 b2 Reverse Reflected a2 Incident Copyright 2000 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 Network Analyzer Basics Copyright 2000 Criteria for Distortionless Transmission Nonlinear Networks • • 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 Time Frequency Copyright 2000 Measuring Nonlinear Behavior 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 8563A LPF LPF Network Analyzer Basics SPECTRUM ANALYZER RL 0 dBm ATTEN 10 dB 10 dB / DIV 9 kHz - 26.5 GHz DUT CENTER 20.00000 MHz RB 30 Hz VB 30 Hz SPAN 10.00 kHz ST 20 sec Copyright 2000 What is the Difference Between Network and Spectrum Analyzers? . Measures known signal Amplitude Amplitude Ratio 8563A measure components, devices, circuits, sub-assemblies contain source and receiver display ratioed amplitude and phase (frequency or power sweeps) offer advanced error Network Analyzer Basics correction 9 kHz - 26.5 Measures unknown signals Frequency Network analyzers: SPECTRUM ANALYZER GHz Frequency Spectrum analyzers: measure signal amplitude characteristics carrier level, sidebands, harmonics...) can demodulate (& measure) complex signals are receivers only (single channel) Copyright can be used for scalar component 2000 test (no Generalized Network Analyzer Block Diagram Incident Transmitted DUT SOURCE Reflected SIGNAL SEPARATION INCIDENT (R) REFLECTED (A) TRANSMITTED (B) RECEIVER / DETECTOR PROCESSOR / DISPLAY Network Analyzer Basics Copyright 2000 Source Supplies stimulus for system Swept frequency or power Traditionally NAs used separate source Most Agilent analyzers sold today have integrated, synthesized sources Network Analyzer Basics Copyright 2000 Incident Signal Separation Transmitted DUT Reflected SOURCE SIGNAL SEPARATION INCIDENT (R) REFLECTED (A) TRANSMITTED (B) RECEIVER / DETECTOR PROCESSOR / DISPLAY • • measure incident signal for reference separate incident and reflected signals splitter bridge directional coupler Network Analyzer Basics Detector Test Port Copyright 2000 Directivity Directivity is a measure of how well a coupler can separate signals moving in opposite directions (undesired leakage signal) (desired reflected signal) Test port Directional Coupler Network Analyzer Basics Copyright 2000 Interaction of Directivity with the DUT (Without Error Correction) 0 Device Return Loss Directivity Data Max DUT RL = 40 dB 30 Add in-phase 60 Network Analyzer Basics Device Device Directivity Frequency Data Min Add out-of-phase (cancellation) Data = Vector Sum Directivity Copyright 2000 Incident Detector Types Transmitted DUT Reflected SOURCE Diode Scalar broadband (no phase information) SIGNAL SEPARATION INCIDENT (R) REFLECTED (A) TRANSMITTED (B) RECEIVER / DETECTOR PROCESSOR / DISPLAY DC RF AC Tuned Receiver IF = F LO F RF RF ADC / DSP Vector (magnitude and phase) IF Filter LO Network Analyzer Basics Copyright 2000 Broadband Diode Detection 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 10 MHz Network Analyzer Basics 26.5 GHz Copyright 2000 Narrowband Detection - Tuned Receiver ADC / DSP 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 10 MHz Network Analyzer Basics 26.5 GHz Copyright 2000 Comparison of Receiver Techniques Broadband (diode) detection 0 dB 0 dB -50 dB -50 dB -100 dB -100 dB -60 dBm Sensitivity higher noise floor false responses Narrowband (tuned-receiver) detection < -100 dBm Sensitivity high dynamic range harmonic immunity Dynamic range = maximum receiver power receiver noise floor Network Analyzer Basics Copyright 2000 Dynamic Range and Accuracy Error Due to Interfering Signal 100 - Error (dB, deg) 10 + Dynamic range is very important for measurement accuracy! phase error 1 magn error 0.1 0.01 0.001 0 -5 -10 -15 -20 -25 -30 -35 -40 -45 -50 -55 -60 -65 -70 Interfering signal (dB) Network Analyzer Basics Copyright 2000 T/R Versus S-Parameter Test Sets S-Parameter Test Set Transmission/Reflection Test Set Source Source Source Transfer switch Transfer switch R1 R R B A B A R2 Port 1 Port 2 Port 2 Port 2 Port 1 Port 1 Fwd RF always comes out port 1 port 2 is always receiver response, one-port cal Network Analyzer Basics available Fwd DUT DUT Rev RF comes out port 1 or port 2 forward and reverse measurements Copyright two-port calibration 2000 Processor / Display Incident Transmitted DUT 50 MH-20GHz NETWORK ANYZER ACTIVE CHANNEL Reflected CH2 START 775.000 000 MHz CH1 START 775.000 000 MHz SOURCE ENTRY STOP 925.000 000 MHz STOP 925.000 000 MHz Hld RESPONSE PASS 2 Cor PRm SIGNAL SEPARATION 880.435 000 MHz 1 PASS Hld 1 STIMULUS R CHANNEL INSTRUMENT STATE 1 Cor INCIDENT (R) REFLECTED (A) TRANSMITTED (B) PRm T 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 PORT 1 1_ -1.2468 dB 1_ -1.9248 dB HP-IB STATUS 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 Cor markers limit lines pass/fail indicators linear/log formats grid/polar/Smith charts Network Analyzer Basics PRm 880.435 000 MHz 1 PASS Hld 1 1 Cor PRm 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 1_ -1.2468 dB 1_ -1.9248 dB Copyright 2000 R L S Frequency Sweep - Filter Test CH1 S 21 log MAG 10 dB/ REF 0 dB CH1 S11 log MAG 5 dB/ REF 0 dB Cor 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 4.000 000 GHz - m1: 0.16 dB m2-ref: 2.145 234 GHz 0.00 dB ref 2 Insertion lossCor x2 1 START 2 000.000 MHz Network Analyzer Basics 2 STOP 6 000.000 MHz Copyright 2000 Output Power (dBm) Power Sweeps - Compression Saturated output power Compression region Linear region (slope = small-signal gain) Input Power (dBm) Network Analyzer Basics Copyright 2000 Power Sweep - Gain Compression CH1 S21 1og MAG 1 dB/ REF 32 dB 30.991 dB 12.3 dBm 1 dB compression: 1 0 START -10 dBm Network Analyzer Basics CW 902.7 MHz input power resulting in 1 dB drop in gain STOP 15 dBm Copyright 2000