"user manual"
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1. Mag 101057 m inia al E D i Stet 4007194245 GHz Pur Ste 149 8 mm Time Domain Stop 15m Cam SETTINGS and CONSTANTS Cable 2 load 24 gt Speed of Light m s Meters to Feet Conversion LIMITATIONS Max Measurable Cable Length ft 69 72 Max Measurable Time s 1 00E 07 Distance Resolution in 0255 Time Resolution s ROHDE amp SCHWARZ Time Gating I Time Gating opens up a whole new range of applications for the Time Domain option of a Network Analyzer I Typical application is to filter out certain parts of the response and display back into the Frequency Domain Measure the return loss looking into this adaptor even though the cable is terminated with an open circuit Cable 2 Open et ROHDE amp SCHWARZ Impulse and Step Response Examples SHORT OPEN impulse and step respone zvx Trace Channel Display System Window Info Help Real 200 mU Ref OU Offs Real 200 mU Ref OU Offs smith chart freq domain windowing Start 11 964108 0 dBm Start 1 1e Domain 964108 MHz r 0 dBm Tre1 Start 1 ns 1 Domain Stop 4 ns 200mU2. x0 xrdt ROHDE amp SCHWARZ z Reflection and transmission short circuited line SHORT 4 9 Reactive behavior Agy 90 e Standing wave Current and voltage are space dependent e Power oscillates along the line 0 ROHDE amp SCHWARZ gt o Parameters wave quantities and their relationship S parameters are the basic measured quantities of a network analyzer They describe how the DUT modifies a signal that is transmitted or reflected in forward or reverse direction For a 2 port measurement the signal flow is as follows m o Pe Forward 5 2 rev Reverse measurement b measurement 1 2 D rev Port 1 DUT Port 2 S4 isthe input reflection coefficient defined as the ratio of the wave quantities b a measured at PORT 1 forward measurement with matched output and a 0 S4 is the forward transmission coefficient defined as the ratio of the wave quantities forward measurement with matched output and a 0 S is the reverse transmission coefficient defined as the ratio of the wave quantities b4 reverse measurement with matched input in the figure above and a 0 to ap 5 is the output reflection coefficient defined as the ratio of the wave quantities bz reverse measurement with matched input in the figure above and 0 to ap measured at PORT 2 See page 59 of the ZVA user manual ROHDE amp SCHWARZ 5 Criteria f
3. BACKGROUND COLOR MI EVM is now 35 dBc at the band edges Poor EVM can result in lost HARDCOPY data which means 1 retransmission of data which means lost Frequency MHz ES oe oe 32 Agenda Network Analyzer Architecture eBlock diagram of ZVA eDirect receiver access ROHDE amp SCHWARZ Directional Coupler Directivity Directivity is a measure of how well a coupler can separate signals moving in opposite directions Atermination at the test port should result in no signal at the b receiver The difference between the coupled signal and the leakage signal is the directivity of the coupler typical values 15 25dB desired reflected undesired leakage 4 signal signal i zm Test port Directional Coupler ROHDE amp SCHWARZ Vector Network Analyzer Block Diagram av Port 1 Port 2 receiver is also known as reference receiver b receiver is also known as measure receiver ROHDE amp SCHWARZ 55 ZVA 4 Port Test Set Reflectometer 2 Reflectometer 4 Reflectometer 3 ZVA 2 Port Test Set with direct receiver access B16 From generator From generator Agenda ee Calibration Importance of calibration ROHDE amp SCHWARZ Measurement Errors Calibration cannot be removed only minimized removed nearly
4. I Describes fundamental performance in pure differential mode operation ROHDE amp SCHWARZ Mixed Mode S Matrix CC Quadrant input reflection reverse transmission Sdd M SdN12 11 Sde 12 Sdd 21 Sdd 21 Sde 22 Scd Sed 12 Scd 21 Scd 22 forward transmission output reflection I Describes fundamental performance in pure common mode operation ROHDE amp SCHWARZ Mixed Mode S Matrix DC Quadrant input reflection reverse transmission Sdd 11 21 Scd 11 21 forward transmission output reflection I Describes conversion of a common mode stimulus to a differential mode response I Terms are ideally equal to zero with perfect symmetry 1 Related to the generation to EMI ROHDE amp SCHWARZ Mixed Mode S Matrix CD Quadrant input reflection reverse transmission Sdd 1 Sdd 12 Sdd 21 544 22 5 S cc Scc 11 Sde 12 2 Sde 22 12 2 22 forward transmission output reflection response I Terms are ideally equal to zero with perfect symmetry 1 Related to the susceptibility of EMI ROHDE amp SCHWARZ Describes conversion of a differential mode stimulus to a common mode Example 1 Tunable Active Filter Trc18 2 2 dB Mag 0 5 dB Ref 23dB Chi Calint 2 of 16 Max 2
5. Ideal Balanced Device Characteristics Gain 1 cE Common mode signal Fully balanced EMI or ground noise er Differential mode signal Gain 1 Differential mode signal BE Common mode signal EMI or ground noise Mi p ROHDE amp SCHWARZ Non Ideal Balanced Device Characteristics Non ideal balanced devices convert modes Differential to common mode conversion _ to differential conversion ROHDE amp SCHWARZ Parameters to Test for a Balanced Device I Performance in pure differential mode D I Performance in pure common mode I Conversion from differential mode to common mode in both directions I Conversion from common mode to differential mode in both directions ROHDE amp SCHWARZ Basic Architecture Definition of Differential Measurements Measurement Principle I VirDi Virtual differential Mode Characterization of balanced DUT as single ended DUT with mathematical calculation of mixed mode S Parameters from single ended S Parameters I TruDi True differential Mode Stimulation of DUT with true differential and common mode signals with calculation of mixed mode S Parameters from error corrected mixed mode wave quantities ROHDE amp SCHWARZ Virtual Differential Measurement X I Single ended measurements with pos
6. RefOU Offs Step Chi Stat 11 964108 MHz r 0 dBm Tre3 Start 1 ns 1 Domain Stop 4 GHz Start 11 964108 MHz 0 dBm Stop 4 GHz Start 1 ns 1e Domain Stop 4ns 511 measurement with no gating Trci dB Mag 10dB RefO dB 1 Trc2 Real 50 mU Ref 150 mU 797 0000 ps 257 43 mU 70 Chi fb Start 19 900498 MHz Pb 0 dBm Stop 4 GHz fb Start 1 ns Time Domain Stop 4 ns 11 3 2014 12 49 ROH DE 5 HWARZ 10 11 2014 Introduction and Fundamentals of VNA s 110 511 measurement with gating dBMag 10dB RefO dB Gat Trc2 Real 50 mU Ref 150 mU S11 797 0000 ps 258 66 mU 10 0 M1 10 yf 11 30 D 40 Lr pp ft 60 70 i Chi fb Start 19 900498 MHz Pb 0 dBm Trc2 fb Start 1 ns Time Domain Stop 4 ns 11 3 2014 1248 PM ROHDE amp SCHWARZ 10 11 2014 Introduction and Fundamentals of VNA s 111 summary of VNA Settings I The Span determines the Time Resolution as follows When in Bandpass Mode Resolution 2 Span When in Lowpass Mode Resolution 1 Span I The of Points and Span determine the Ambiguity Range by the following relation Range 1 Af 1 Span t of points
7. 23 Background m m m 24 When setting up a TOR measurement the two key setup parameters ofthe Network Analyzer are n 9 WI a n 1 5 25 the Span and the Number of Points The way that modern Network Analyzers make measurements 26 is by directly measuring the response ofthe device in the frequency domain and then calculating the Time Domain 27 Impulse Response by performing an Inverse Fourier Transform IFT 28 WI d t h 5 n d a ce rta n a 9 nt of S 28 Ideally the time domain response would be from a single infinitely narrow impulse Dirac Delta function The frequency transform 30 ofthe ideal Dirac Impulse is an infinite spectrum that is completely continuous However we know when measuring with a 131 Network Analyzer we measuring a Finite Spectrum Span at Discrete Points of Points The consequences of this are two fold b e S u res S r d n n 32 1 Due to the Finite Spectrum Measured the calculated Impulse in the Time Domain is not infinitely Narrow 33 2 Due to the Discrete Measurement Points instead of Continuous points the period ofthe impulse in the time 34 domain is not Infinity i e the impulse will be replicated at regular time intervals called the Pulse Repetition Frequency PRF 35 W h at a re we t r 1 n to m eas 9 re 36 Due to consequence 1 we know thatthe resolution in the time domain is limited Consequence 2 me
8. determine the source of the reflections I 4 d open ROHDE amp SCHWARZ But what is a TDR measurement I TDR measurement we send a pulse down a transmission line and then we record in time the reflections that come back out of the transmission line I This can be done with fast power supply and a fast oscilloscope I The goal is to measure the transient traveling waves on the transmission line leading to the device under test Step Generator Device under Test The time delay tells us the distance to the load Sampler 4 The reflected wave magnitude and phase tells us the impedance of the load ROHDE amp SCHWARZ And what are the challenges I Generating a very clean and fast pulse 1 stepped pulse in the time domain generates all frequencies in the frequency domain 2 The pulse generator needs to be matched to the transmission line Mismatches need to be calibrated out of the measurement 3 The oscilloscope needs to sample at a very high frequency These pulses are traveling at the speed of light if the transmission line has an air dielectric 4 The oscilloscope also needs to be matched to the transmission line 1 These challenges match up well with the features of modern vector network analyzers Aliasing in the time domain I Aliasing results from the fact that the Network Analyzer measures the spectrum at a finite number of discrete measuremen
9. which be quantified as Jitter Signal Quality which be described with parameters such as ringing crosstalk etc I Jitter can be measured directly in the time domain using an oscilloscope or in the frequency domain using a phase noise analyzer I Signal Quality can be measured in the time domain using a high speed TDR technique or in the frequency domain using a vector network analyzer s parameters IEEE P802 3ap Task Force uses S parameters as test cases for proposed solutions to the problem of 10 Gbit s ethernet over backplanes ROHDE amp SCHWARZ Balanced Devices Ideal device responds to input signals and rejects common mode signals Differential mode signal WP W Balanced to single ended Common mode signal EMI or ground noise Differential mode signal Fully balanced Common mode signal AP or ground noise A ROHDE amp SCHWARZ 73 Balanced devices Why Balanced Design Components with balanced design Amplifiers Mixers Filters e g SAW filters e PCB layout mobile phones e LAN adapters converters filters PC components HDD control etc Almost all signals high speed serial data signals ROHDE amp SCHWARZ Advantages High noise immunity Minimizes Power and ground plane noise Minimizes EMI susceptibility Minimizes Cross talk Low radiated noise High integration density Lower power consumption
10. with calibration ROHDE amp SCHWARZ Calibration 1 We only want to measure our DUT device under test and nothing else I Need to remove the phase and amplitude response of our test setup I Connect known standard something we know to the calibration plane Calibration Plane Types of Error Correction e Response normalization simple to perform only corrects for tracking errors Stores reference trace in memory ihm then does data divided by memory e Vector requires more standards requires an analyzer that can measure phase accounts for all major sources of systematic error Em thru Si Ed ROHDE amp SCHWARZ 45 Vector Error Correction e Process of characterizing systematic error terms Measure known standards Remove effects from subsequent measurements e 1 port calibration reflection measurements Only systematic error terms measured Directivity source match and reflection tracking e Full 2 port calibration reflection and transmission measurements 10 systematic error terms measured crosstalk assumed to be zero Usually requires 7 measurements on four known standards TOSM Thru need not be characterized unknown thru calibration e Standards defined in cal kit definition file Network analyzer contains standard cal kit defini
11. 1 t dB Mag 0 5 dB Ref 23dB Ch2 Calint 20 0 Gain compression true differential virtual differential Chi Start 25 dBm Freq 1 GHz Stop 0 dBm Ch2 Start 28 dBm Freq 1 GHz Stop 3 dBm 3 8 2007 1 10 PM True differential power axis has been shifted by 3 dB to equalize voltage amplitudes ROHDE amp SCHWARZ oummary TruDi vs VirDi I Passive Devices Linear operation TruDi and VirDi give exactly the same results I Active Devices Non linear operation Significant difference between TruDi and VirDi TruDi represents the real operating conditions of a device 1 TruDi Measurements Requires two phase coherent sources Ability to set amplitude and phase independently Relative phase stability of VNA sources is crucial for reproducible results ROHDE amp SCHWARZ Applications of TDR I Localization of Faults in Transmission Lines This is the 1 application that think of for TDR measurements Examples include localizing a fault on an underground cable or a cable running up a tower Test to see if an antenna is properly connected Check if an amplifier or filter is presenting the expected impedance ROHDE amp SCHWARZ Applications of TDR I Moving the Reference Plane of RL measurements This is the second most common use for TDR In the frequency domain we see all the reflected signals separating the results in the time domain we can
12. Evaluating signal integrity with a Vector Network Analyzer DUNG Pul ROHDE amp SCHWARZ ROHDE amp SCHWARZ ROHDE amp SCHWARZ USA INC 7700 Irvine Center Drive Suite 100 Irvine CA 92618 Mobile 480 231 1736 Barry Adkins rsa rohde schwarz com Technical Support Barry Adkins 888 TEST RSA 888 837 8772 RF Application Engineer www rohde schwarz com AZ UT NM NV and No CA Region Agenda Scalar vs Vector analysis Uses for each Transmission Lines S Parameters Wave quantities and wave ratios How S Parameters are derived from wave quantities Network Analyzer Architecture eBlock diagram of ZVA Calibration Importance of calibration Use of calibration manager on the ZVA Signal Integrity measurements domain Balanced devices ROHDE amp SCHWARZ 6 opectrum Analyzers vs Vector Network Analyzers Measures Signals Measures Devices ROHDE amp SCHWARZ 7 0 Scalar Network Analysis Basic scalar analyzer can be a signal generator and a power meter Drawbacks are speed dynamic range and no phase information Advantage is cost Scalar Network Analysis set up with power meter GPIB _ Software FreRes R amp SApp Note1 09 ROHDE amp SCHWARZ 2 ocalar Network Analysis Basic scalar analysis can be done with a spectrum analyzer tracking generator or external generator e Drawback is cost compared to signal generator
13. Use Lowpass Mode if the sign of the Real Part of is important e g for a Short Circuit Response Bandpass Mode can be used when only concerned with Magnitude measurements Frequency Windowing affects the shape of the main and side lobe responses in the Time Domain I Use Time Gating to filter out undesired discontinuities of the DUT Time Gate Windowing affects the shape of the main and side lobe responses in the Frequency Domain ROHDE amp SCHWARZ What is the Measurement Frequency 1 The max frequency for the VNA can be calculated from the required rise time of the data ROHDE amp SCHWARZ 23 2013 Signal Integrity Testing with a VNA ZVA24 VECTOR NETWORK ANALYZER 10 _ 24 ROHDE amp SCHWARZ 114
14. and sensor Still no phase information Advantages are speed dynamic range and spectrum analyzer can be used for other measurements calar Network Analysis spectrum analyzer with tracking generator 1 ROHDE amp SCHWARZ 10 What Devices do Vector Network Analyzers Test Filters RF Switches Couplers Cables Amplifiers Antennas Isolators Mixers upconverters downconverters also sometimes referred to as transmitters and receivers Most 2 or more port devices and some 1 port devices ROHDE amp SCHWARZ Agenda Scalar vs Vector analysis Uses for each Transmission Lines e S Parameters Wave quantities and wave ratios How S Parameters are derived from wave quantities Network Analyzer Architecture eBlock diagram of ZVA Calibration Importance of calibration Use of calibration manager on the ZVA e Signal Integrity measurements domain Balanced devices Optical Analogy to RF Transmission Network analyzers measure transmitted and reflected signals relative to the incident signal Scalar analyzers measure magnitude only vector analyzers measure magnitude and phase of these signals Do Transmitted Incident Reflected ROHDE amp SCHWARZ 13 Transmission Lines Coax Cable Parallel Lines pon a Microstrip Line Waveguide ROHDE amp SCHWARZ 14 Transmission Line Terminated with Zo Zo chara
15. ans thatthere is a limitto 5 37 the unambiguous measurement time period This is because there will be replications of the pulse in the time domain that are resulting from the 2 E Network Analyzer s calculation and not from the DUT itself Spurious Results The time period is known as the Alias Free Range high dynamic range or a high MEC J 41 The time resolution and thus distance resolution can be calculated directly from the Span Time Resolution 1 Span Hz 1 42 The Alias Free Range be calculated by the formula Alias Free Range 1 Span of Points 43 The Alias Free Range is denoted in the spreadsheet above by the parameter Max Measurable Time s a 9 n p rec 1 S e 44 get either ofthe above parameters into distance simply multiply by the Speed of Light and divide by S RT Dielectric Constant 45 46 Using Spreadhseet above n r m X 4T The goal is to achieve the desired measurement resolution and Max Measurable cable length simultaneously Additionally it is 48 desired to use the minimum number of points to achieve this since the fewerthe measured points the faster the measurement speed 48 The maximum number of points that be set the Rohde amp Schwarz ZVX is 20 001 50 51 M bi Sheet1 lt zag NUM ROHDE amp SCHWARZ Example Distance to Fault Tace Channel Display System Window Ifo Feb 5m
16. cteristic impedance of Zs ZO transmission line Or RR D A C Vrei 0 all the incident power is absorbed in the load ROHDE amp SCHWARZ 15 Transmission Line Terminated with Short Open Standing Wave P sum of incident and reflected waves Vre OPEN In phase 0 SHORT Out of phase 180 ROHDE amp SCHWARZ 16 Agenda zb S Parameters Wave quantities and wave ratios How S Parameters are derived from wave quantities ROHDE amp SCHWARZ 20 High Frequency Device Characterization Port 1 Incident 1 receiver Reflected 1 receiver REFLECTION Reflected bt Incident Return SWR Loss S Parameters Impedance 511 5 Reflection Admittance Coefficient R jX T p G jB ROHDE amp SCHWARZ 21 Port 2 Transmitted b2 receiver TRANSMISSION Transmitted b2 Incident at P Gain Loss Insertion S Parameters Phase Sons Transmission Coefficient Lz Group Delay Reflection and transmission Termination with line impedance MATCH I Current and voltage in phase I Perfect traveling wave I No space dependence I Perfect power transmission from source to drain ROHDE amp SCHWARZ 2 Reflection and transmission Open line OPEN Li e Reactive behavior 90 e Standing wave Current and voltage are space dependent e Power oscillates along the line
17. or Distortionless Transmission Constant amplitude over Linear phase over bandwidth of interest bandwidth of interest l I Frequency l J Frequency Magnitude Phase Distortion is indicated by Deviation from constant amplitude Deviation from linear phase or stated another way Non constant group delay ROHDE amp SCHWARZ Group Delay Group delay ripple Frequency tg Average delay B EE 7X Ao _ E Deviation from linear phase Frequency e VNAs calculate group delay from phase measurement across frequency e Group delay ripple indicates phase distortion deviation from linear phase e Average delay indicates electrical length of DUT e Aperture of group delay measurement is very important ROHDE amp SCHWARZ Real world example of distortion OFDMA and EVM I Consider an OFDMA signal that is 20 MHz wide 1201 sub carriers 1 With nearly flat amplitude and phase response EVM is 55 dBc a fairly low value FFT 4 di Frequency Y HARDCOPY 10 15 Time ROHDE amp SCHWARZ I Introduce linear amplitude and phase distortion via a channel filter which primarily impacts the band edges Rohde amp iz EUTRA LTE Bhd Software 2 3 Beta 8 nf eve 15 FULL Syn ath TUE SCREEH Maximum 33 0 Minimum 54 224 dB 3 2 160 MHz SPLIT SCREEN AV
18. t points I In the time domain this results in the time response being copied at regular intervals Fourier transform of a comb spectrum is a comb spectrum I Ambiguity range At 1 Af where Af spacing of measurement points ROHDE amp SCHWARZ liasing in the time Nwa aliasing zvx Trace Channel Display System Window Info Help dBMag 10dB RefOdB Smo omain Number of Points Frequency Step Size ChI Start 1 GHz Pwr 0 dBm Trc1 Start 10ns Time Domain Stop 10 GHz Stop 90ns Start 1 GHz Pwr 0 dBm Start 10 ns Time Domain Stop 10 GHz Stop 90ns Tradeoffs and settings 1 We need to pick a frequency span and number of points 1 1 1 We will end up with an alias free B 2 3 ROHDE amp SCHWARZ 1 5 range and a time resolution 7 7 Utility for Time Domain Reflectometry TDR Measurements with RS ZYX 8 A spreadsheet can help us with B Yi MATERIAL 1 0GHz VOP Dolay 12 th IS 13 3 00E 08 Meters to Feet Conversion 328 15 18 RESULTS e then pick a window function NUM 18 52 59 19 t h f r n d m n 20 21 e irequency doma 2
19. t processing using linear superposition 1 Applicable for all passive devices and active devices operating in their linear region I Large deviations compared to True Differential in large signal operation especially in terms of compression curve characteristics Nonlinear behavior of the DUT prohibits linear superposition ROHDE amp SCHWARZ 7 True Differential Mode I Coherent sources Generation of true differential and common mode stimulus signals At least one signal output can be adjusted in amplitude and phase with respect to the other I Simultaneous measurement of two reference signals a waves and two measurement signals b waves I Four port calibration in the reference plane Vector corrected measurement of single ended waves or voltages I Calculation of true differential S Parameters from vector corrected wave quantities ROHDE amp SCHWARZ Sweep modes R amp S ZVA K6 differential mode 180 common mode 0 Be Edt Vert Display Cursor Meas Mak Math App Lilies Button Edt Vert Run Sample 02 Fob 07 16 19 28 Position 460 Fai 2 100mv 125ps div Tony 152 100 20 065 IT 2 5ps pt di Coherent signals of arbitrary phase and amplitude imbalance are possible Sweep Modes Frequency Phase Phase of the stimulating signal can be swept from 0 to 180 Magnit
20. tions CAL KIT DEFINITION MUST MATCH ACTUAL CAL KIT USED User built standards must be characterized and entered into user cal kit ROHDE amp SCHWARZ 46 File Trace Channel Display System Window Info Help la x dB Mag 10dB RefOdB Cal Mem2 Trc1 dB Mag 10 487 Ref 0 dB uncalibrated 1 port cal Start 1 GHz Pwr 0 dBm Stop 2 GHz Methods of De embedding 1 Simple delay port extension Simply moves reference plane mathematically Assumes fixture is ideal transmission line with fixed delay Simple loss model can optionally be included Delay be entered explicitly or measured with an open or short I Fixture Compensation Models fixture vs frequency delay and loss Does not assume fixture is simple ideal transmission line Compensation can be measured with open short or both AFR can also be done 1 De Embedding Models fixture as lumped element network Uses measured S parameters of fixture to de embed Most accurate but S parameters can be difficult to measure for some fixtures ROHDE amp SCHWARZ 1 ru iE Sate US Soa j etater ie SWE Signal Integrity measurements domain Balanced devices ROHDE amp SCHWARZ 70 Introduction Signal Integrity I Signal Integrity is a set of measures of the quality of an electrical signal 1 Two Key Aspects of SI Timing
21. ude Variation of the relative magnitude of the differential signals Classical calibration techniques sufficient full two port Investigation of the DUT under real conditions ROHDE amp SCHWARZ Typical measurements quality parameters Differential and common mode insertion loss Differential and common mode return loss NEXT Measurements Near End Crosstalk FEXT Measurements Far End Crosstalk Amplitude Imbalance Phase Imbalance Common Mode Rejection Ratio CMRH ROHDE amp SCHWARZ Port Configurations for Differential DUT 1 Physical single ending ports gt logical balanced ports lt physical ports logical ports Port 1 Port 2 I Different impedances for common mode and differential mode differential mode ideally matched 100 Q 2 Z0 common mode ideally matched gt 25 1 2 240 ROHDE amp SCHWARZ Modal Decomposition Method Mixed Mode S Parameter Matrix Z Differential Mode Common Mode stimulus stimulus Logical Port 1 Logical Port 2 E 9 4411 5 4412 5 dell 5 4 12 iur Saa21 Saaz Sacz Sa 5 2 Naming Convention S mode meas mode stim port meas port stim ROHDE amp SCHWARZ Mixed Mode S Matrix DD Quadrant input reflection reverse transmission Bagno San Sac un Sac 22 Sed 11 Sco 12 Bun Sanz no Sen forward transmission output reflection
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