NORME INTERNATIONALE CEI IEC INTERNATIONAL STANDARD 60512 25 1 Première édition First edition 2001 07 Connecteurs pour équipements électroniques � Essais et mesures � Partie 25 1 Essai 25a � Taux de d[.]
Domaine d’application et objet
La présente partie de la CEI 60512 s’applique aux systèmes d’interconnexion, tels que les connecteurs électriques, les embases et les cordons.
This standard outlines testing procedures to measure the electrical and magnetic coupling between an emission line and an induced line in an interconnection system It details two methods: a time measurement method (Method A) and a frequency measurement method (Method B) for asymmetric or differential transmissions Additionally, it describes insertion techniques and reference mounting techniques.
Définitions
Pour les besoins de la présente partie de la CEI 60512, les définitions suivantes s’appliquent.
1.2.1 signal d’émission front d’onde (dans la mesure temporelle) ou forme d’onde sinusọdale (dans la mesure en fréquence)
The crosstalk rate is the ratio of the coupled (induced) signal in the conductor or pair of conductors of the induced line to the amplitude of the signal in the conductor or pair of conductors of the emitting line Both signals are measured in the same unit, either voltage or current, and the ratio can be expressed as a percentage or in decibels (dB).
1.2.3 paradiaphonie (NEXT) taux de diaphonie calculé sur la ligne induite proche de l’entrée du signal de la ligne d’émission
(signal de la source) C’est le rapport entre l’amplitude du signal induit à l’extrémité proche de la ligne induite et l’amplitude du signal à l’extrémité proche de la ligne d’émission
The tele-diaphony (FEXT) measures the crosstalk rate calculated on the induced line near the receiving end of the transmission line It represents the ratio of the induced signal amplitude at the far end to the emission line signal amplitude at the near end.
The rise time of the system is measured using the setup in place, without the sample, and with a filter or shaping function Typically, the rise time is assessed between the 10% levels.
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This part of IEC 60512 applies to interconnect assemblies, such as electrical connectors, sockets and cable assemblies.
This standard outlines test procedures to assess the electric and magnetic coupling between driven and quiet lines in an interconnect assembly It details both time domain (method A) and frequency domain (method B) approaches for single-ended and differential transmission, along with techniques for insertion and reference fixtures.
For the purpose of this part of IEC 60512, the following definitions apply.
1.2.1 drive signal a step waveform (in the time domain) or a sinusoidal waveform (in the frequency domain)
The crosstalk ratio measures the amount of signal that is coupled into a quiet conductor or conductor pair compared to the signal in the driven conductor or conductor pair This ratio can be expressed in either percentage or decibels (dB), with both signals measured in the same units of voltage or current.
The near end crosstalk ratio (NEXT) is defined as the crosstalk ratio measured on the quiet line near the signal source of the driven line It represents the relationship between the signal amplitude of the near end quiet line and the signal amplitude of the near end driven line.
The far end crosstalk ratio (FEXT) is defined as the crosstalk ratio measured on the quiet line near the receiving end of the driven line It represents the relationship between the signal amplitude of the far end quiet line and the signal amplitude of the near end driven line.
1.2.5 measurement system rise time rise time measured with fixture in place, without the specimen, and with filtering (or normal- ization) Rise time is typically measured from 10 % to 90 % levels
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The environmental impedance of the sample refers to the impedance presented by the setup to the signal conductors of the sample This impedance results from transmission lines, load resistances, connected signal sources and receivers, as well as disruptive mounting elements.
1.2.7 amplitude du front d’onde différence de potentiel entre les niveaux 0 % et 100 %, sans tenir compte des variations de part et d’autre, comme montré à la figure 1
The absolute standard setup serves as a reference without a test sample, featuring identical crosstalk characteristics to the test setup This configuration may or may not be part of the test board.
Equipement
Méthode A, mesure temporelle
2.1.1.1 Un générateur de front d’onde est utilisé pour la ligne d’émission et un oscilloscope contrôle la ligne induite Dans une application en différentiel, les deux équipements doivent être capables de fonctionner avec des signaux différentiels En général, cela signifie des sorties complémentaires avec possibilité d’ajuster l’amplitude et le décalage entre les signaux, et deux entrées avec un affichage de la somme et de la différence Des fonctions de filtrage et de remise en forme doivent être disponibles pour faire varier le temps de montée En général, on utilise un réflectomètre en domaine temporel (RDT).
It is important to remind testing technicians of the limitations associated with all mathematical operations performed by an instrument, such as reshaping or filtering software.
Lorsque des sondes sont utilisées, elles doivent être adaptées en temps de montée et en caractéristiques de charge du circuit (résistance et capacité).
Méthode B, mesure en fréquence
For optimal measurements, a network analyzer is preferred When a wider dynamic range is required, an alternative setup may include a signal generator paired with a spectrum analyzer or a vector network analyzer, especially for full two-port calibration measurements To enhance measurement sensitivity, additional equipment such as wideband output amplifiers or low-noise preamplifiers can be utilized Multi-port network analyzers and appropriate software, or baluns, are also effective for differential measurements.
Montage
Agencement des conducteurs de l’échantillon
For each measurement, the emission lines and induced lines must be arranged as specified in the reference document In cases where the emission signal is differential and unbalanced, the common mode energy should be adjusted accordingly Additionally, adjacent signal lines should be matched whenever possible, as electrically long adjacent signal lines can resonate and introduce errors into the results Unless stated otherwise, a ground line should be used for each end of a signal line, ensuring all grounds are common If a differential measurement is performed, a differential pair should be used for the ground line For an example, refer to Figure A.4.
Adaptation
The distant ends of the emission lines and both ends of the induced line must be adjusted according to the specified impedance of the sample within its environment, utilizing one of the methods illustrated in Figures A.2 and A.3 It is essential to minimize the reactive component of the resistive matching across the entire range of test frequencies.
The geometry of the assembly and the materials used can affect measurements due to disruptive mounting elements Generally, the intended use of the product determines the most suitable method for its installation.
Diaphonie
En général, il n’est pas possible de séparer la diaphonie du montage de celle de l’échantillon.
When common mode currents are present in a circuit conductor, they couple through common impedance, adding to the actual crosstalk It is essential for the reference document to specify the circuit configurations to minimize their impact on crosstalk and ensure that matching impedances are replicated If not specified, their influence should be minimal compared to the actual crosstalk of the sample.
Since the test card tracks or cable connection techniques can affect crosstalk, it is advisable to include an absolute standard in the setup to measure the crosstalk of the assembly.
Montage pour la technique d’insertion
The setup must be designed to facilitate the measurement of crosstalk with or without the test sample, as illustrated in Figure A.1 If symmetrizers are employed for symmetric measurements or minimum loss circuits for impedance matching, refer to Figures A.2 and A.3, these devices are integrated into the setup.
Technique du montage de référence
This technique employs a separate setup that integrates both the near and far ends to measure the crosstalk of the assembly The setup must replicate the sample assembly but without the sample itself If circuits are involved, they should include the connector layout, pathways, bends, and angles Additionally, if balancers are used for balanced measurements or minimal loss circuits for impedance matching, refer to Figures A.2 and A.3, as these are included in the setup.
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For each measurement, it is essential to fixture the driven and quiet lines as specified in the reference document In cases where the drive signal is differential and unbalanced, the common mode energy must be terminated Additionally, adjacent signal lines should be terminated when feasible to prevent resonance from electrically long lines, which can introduce errors Unless stated otherwise, a 1:1 signal-to-ground ratio should be maintained, with all grounds commoned at each end for differential measurements Refer to figure A.4 for an example.
The driven lines' far end and the quiet line's ends must be terminated in the specimen environment impedance as specified, utilizing one of the methods illustrated in figures A.2 and A.3.
Care should be taken to minimize the reactances of the resistive terminations over the range of test frequencies.
NOTE The fixture geometry and materials may impact the measurements due to the fixture parasitics Usually, the product's intended use dictates the most meaningful way to fixture it.
Separating fixture crosstalk from specimen crosstalk is often challenging, especially when ground currents merge in a fixture conductor, leading to common impedance coupling that exacerbates crosstalk To minimize the fixture's crosstalk contribution, the reference document must clearly specify the fixture and ensure that termination impedances are replicated In the absence of such specifications, the fixture's contributions should remain relatively minor compared to the crosstalk from the actual specimen.
To minimize crosstalk, it is essential to incorporate an isolation standard in the measuring fixture, as the test board footprint and cable assembly termination technique can greatly influence crosstalk levels.
The fixture is designed to measure crosstalk both with and without the specimen, as illustrated in figure A.1 It incorporates baluns for balanced measurements and minimum loss pads for impedance matching, as shown in figures A.2 and A.3.
This technique employs a dedicated fixture that integrates both near end and far end for measuring fixture crosstalk The fixture is a replica of the specimen fixture, excluding the specimen itself It incorporates traces that encompass fixture connectors, vias, bends, and corners Additionally, if baluns are utilized for balanced measurements or minimum loss pads for impedance matching, as illustrated in figures A.2 and A.3, these components are also part of the fixture.
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Description
Connecteurs séparables
Une paire de connecteurs accouplés.
Cordon
Des connecteurs et des câbles assemblés, et des connecteurs accouplés.
Embase
Une embase et un dispositif d’essai ou une embase et un adaptateur d’embase pour accouplement.
The far end of the emission lines and both ends of the induced lines must be loaded with the specified environmental impedance of the sample, utilizing one of the methods shown in Figures A.2 and A.3 To enhance accuracy, it may be necessary to load adjacent signal lines as well.
Méthode A, mesure temporelle
4.1.1 Disposer l’échantillon au minimum à 5 cm de tout objet susceptible d’affecter les résultats de mesure.
4.1.2 Mesure de référence et diaphonie du montage
Crosstalk is influenced by the rise time of the wavefront and the amplitude within the sample The rise time is extended by the setup, which is why the measured rise time of the system is always greater than that produced by the equipment and must be accurately measured This rise time should be assessed between the 10% and 90% levels.
The assembly introduces additional crosstalk to the sample's crosstalk It may include minimal loss circuits if utilized If the reference document accurately describes the assembly, its impact on crosstalk is understood, making the measurement of the assembly's crosstalk optional These results are presented in a graph of amplitude versus time Measurements of the rise time, emission amplitude, and assembly crosstalk are conducted using one of the following techniques.
Assemble the setup so that the near end is connected to the far end without the sample in between, and connect the oscilloscope and pulse generator to the appropriate locations in the emission line setup For balanced measurements, adjust the amplitudes of the negative and positive fronts to be identical and disable the offset function between the generator signals, assuming the setup is designed for equal delays across all lines In the case of multiple emission lines operating simultaneously, ensure that the amplitudes are the same and disable the offset function between the signals.
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For this test procedure, the test specimen shall have more than one signal line and shall be as follows.
Assembled connectors and cables, and mating connectors.
A socket and test device or a socket and pluggable header adapter.
The termination of the driven lines at their far end, along with both ends of the quiet line(s), must be conducted in accordance with the specified specimen environment impedance, utilizing one of the methods illustrated in figures A.2 and A.3.
For increased accuracy, it may be necessary to terminate the adjacent signal lines.
4.1.1 Place the specimen a minimum of 5 cm from any objects that would affect measured results.
4.1.2 Reference measurement and fixture crosstalk
Crosstalk is influenced by the drive step rise time and amplitude of the specimen The fixture increases the drive step rise time, resulting in a measurement system rise time that exceeds that of the test equipment Therefore, it is essential to measure the rise time, which should be assessed from the 10% to 90% levels.
Fixture crosstalk contributes to overall specimen crosstalk, and the use of minimum loss pads can affect this contribution If the reference document clearly outlines the fixture's characteristics, measuring fixture crosstalk becomes optional The results are presented as a magnitude versus time plot, and it is essential to measure the system's rise time, drive amplitude, and fixture crosstalk using one of the specified techniques.
Assemble the fixture by connecting the near end to the far end without the specimen in between, and ensure the oscilloscope and pulse generator are properly connected to the driven line fixture For accurate balanced measurements, equalize the amplitudes of positive and negative steps and eliminate any skew at the signal source, assuming the fixture is designed with equal delays across all lines When dealing with multiple simultaneously driven lines, it is essential to match amplitudes and remove skew for optimal results.
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If the number of emission lines to be excited simultaneously exceeds the equipment's capabilities or if the removal of offsets between channel signals is necessary, the lines can be activated one at a time, and the crosstalk can be calculated through superposition.
NOTE Cela peut ne pas être adapté pour les mesures de télédiaphonie des câbles longs.
Measure the rise time of the wavefront and the amplitude of the transmitted emission signal through the setup alone If necessary, this can be performed using the setup with the sample Adjust the filter (or reshaping) so that the measured rise time matches the required value or a value from Table 1.
Connect the oscilloscope to the specified location on the induced line as indicated in the reference document Measure the crosstalk amplitude of the setup with the sample removed Calculate the crosstalk rate by dividing the crosstalk amplitude by the wavefront amplitude and express it as a percentage Unless stated otherwise, record the peak values and their signs.
4.1.2.2 Technique du montage de référence
To connect the oscilloscope and pulse generator correctly in the emission line, ensure that the negative and positive pulse amplitudes are set to be equal for balanced measurements Additionally, disable the offset function between the signals of the generator.
(cela prộsume que le montage a ộtộ conỗu pour des retards identiques sur toutes les lignes).
Dans le cas de plusieurs lignes d’émission en simultané, faire en sorte que les amplitudes soient les mêmes et désactiver la fonction décalage entre les signaux.
If the number of emission lines to be excited simultaneously exceeds the equipment's capabilities or if the removal of offsets between channel signals is necessary, the lines can be activated one at a time, and the crosstalk can be calculated through superposition.
Measure the rise time of the wavefront and the amplitude of the transmitted emission signal through the setup alone (If necessary for telephony, this can be done using the setup with the sample.) Adjust the filter (or reshaping) so that the measured rise time matches the required value or a value from Table 1.
Tableau 1 – Temps de montée recommandés du système de mesure
Temps de montée du signal préconisé pour l’application ps
Temps de montée du système de mesure ps
Connect the oscilloscope to the induced line location of the reference setup as specified in the reference document Measure the amplitude of the crosstalk in the setup Calculate the crosstalk rate by dividing the amplitude of the crosstalk by the amplitude of the wavefront and express it as a percentage Unless stated otherwise, record the peak values and their signs.
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When the simultaneous driving of lines surpasses the equipment's capacity or when addressing channel skew elimination is critical, it is advisable to drive the lines individually and calculate the crosstalk using superposition.
NOTE This may not be suitable for far end crosstalk measurements of long cable assemblies.
Méthode B, mesure en fréquence
4.2.1 Disposer l’échantillon au minimum à 5 cm de tout objet susceptible d’affecter les résultats mesurés.
4.2.2 Etalonnage (mesure de référence) et mesure de la diaphonie du montage
When using symmetrizers for symmetric measurements or low-loss matching circuits for impedance adaptation, as illustrated in figures A.2 and A.3, these devices fall under the term "mounting." If the reference document defines the mounting in such a way that its crosstalk is known, then measuring the crosstalk of the mounting becomes optional.
Unless stated otherwise, all measurement results must include at least 200 frequency points It is advisable to create a graph of amplitude versus frequency with a vertical scale of 10 dB per division and a logarithmic frequency sweep When applicable, results for a given frequency should be presented in a table according to the guidelines of the reference document.
Assemble the setup so that the near end is connected to the far end without the sample being in between Connect the network analyzer ports to the appropriate locations on the emission line setup Perform a through calibration.
When required by the reference document, the measurement may be referenced against the emission line output instead of the input, and this calibration is performed with the sample in the setup.
Connecter le port de réception à l’endroit spécifié dans le document de référence de la ligne induite.Mesurer le taux de diaphonie du montage en décibels (dB) sans l’échantillon.
Unless otherwise specified in the reference document, a complete calibration of both ports should not be performed, as a calibration standard cannot be connected to this setup.
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To ensure accurate measurements, connect the oscilloscope to the quiet line and the step generator to the driven line at the specified locations For balanced measurements, ensure that positive and negative steps have equal amplitudes and eliminate any skew at the signal source, assuming the fixture is designed with equal delays across all lines When dealing with multiple simultaneously driven lines, it is essential to match amplitudes and remove skew for reliable results.
When the simultaneous driving of lines surpasses the equipment's capacity or when addressing channel skew elimination is critical, it is advisable to drive the lines individually and calculate the crosstalk using superposition.
To measure the specimen-with-fixture crosstalk amplitude, calculate the crosstalk ratio by dividing this amplitude by the step amplitude and express the result as a percentage Record the peak values and their signs unless otherwise specified.
When interpreting results, it is crucial to consider that fixture crosstalk may reach levels comparable to specimen-with-fixture crosstalk Therefore, subtracting fixture crosstalk from the measurement is not a valid approach.
4.2.1 Place the specimen a minimum of 5 cm from any objects that would affect measured results.
4.2.2 Calibration (reference measurement) and measurement of fixture crosstalk
Baluns utilized for balanced measurements and minimum loss pads for impedance matching, as illustrated in figures A.2 and A.3, are categorized under the term "fixture." When the reference document defines the fixture with a known crosstalk contribution, measuring the fixture's crosstalk becomes optional.
All measurement results must include at least 200 frequency points unless stated otherwise It is recommended to create a magnitude versus frequency plot with a vertical scale of 10 dB per division and a logarithmic frequency sweep Additionally, single frequency results should be presented in a table, as outlined in the reference document.
Assemble the fixture by connecting the near end to the far end without placing the specimen in between Next, connect the network analyzer ports to the designated locations on the driven line fixture and conduct a "through" calibration If the reference document indicates that measurements should be referenced to the output of the driven line instead of the input, ensure to perform this calibration with the specimen installed in the fixture.
Connect the receiver port to the quiet line location required in the reference document.
Measure the fixture crosstalk ratio in decibels (dB) without the specimen.
NOTE Unless specified by the reference document, a full 2-port calibration should not be performed because calibration standards cannot be attached to the fixture.
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Assemble the setup so that the near end is connected to the far end without the sample being in between Connect the signal generator and the spectrum analyzer to the appropriate locations in the emission line setup Measure the reference.
Lorsque cela est requis, le signal de référence peut être mesuré à l’extrémité lointaine de l’échantillon, l’échantillon étant inclus dans la mesure.
Without altering any equipment settings, connect the spectrum analyzer to the induced line at the specified locations in the reference document Measure the crosstalk of the setup in dBm without the sample Subtract these results from the reference measurement (in dBm) to obtain the crosstalk of the setup in dB.
4.2.2.2 Technique du montage de référence
Create a reference setup that lacks a specific function but is otherwise identical, incorporating both the near and far ends Connect the network analyzer, signal generator, or spectrum analyzer to the appropriate points in the emission line setup Perform a through calibration using the network analyzer or conduct a reference measurement with the signal generator and spectrum analyzer Connect the receiving port of the network analyzer or spectrum analyzer to the induced line of the reference setup as indicated in the reference document Measure the crosstalk of the setup in dB (for the network analyzer) or in dBm (for the spectrum analyzer) without the sample To obtain the crosstalk rate of the setup using a spectrum analyzer, divide this measurement by the reference measurement.
4.2.3 Mesure de la diaphonie de l’échantillon
4.2.3.2 Connecter le signal d’entrée à la ligne d’émission et le port de réception de l’analyseur de réseau ou de l’analyseur de spectre de la ligne induite aux endroits requis.
Pour tous les essais
The arrangement of mass contacts and signals within the sample for each measurement must be clearly defined At a minimum, it is essential to identify the emission conductors, the induced conductor(s), and the associated adjacent masses.
Unless otherwise specified for asymmetric measurements, the same number of signal and ground lines should be used Crosstalk must be measured on the nearest (adjacent) line or the closest lines induced by coupling to the emission line.
Unless otherwise specified for differential measurements, the same number of signal pairs and ground lines must be utilized Crosstalk should be measured on the nearest (adjacent) line or the closest lines induced by coupling to the emission line.
5.1.2 Type de mesure, asymétrique ou différentielle.
5.1.4 Points ó la diaphonie doit être mesurée sur la ligne induite.
5.1.5 Le point ó le signal d’émission doit être appliqué sur la ligne d’émission.
5.1.6 Spécifier si la mesure de référence doit être effectuée avec ou sans l’échantillon.
Uniquement pour les mesures temporelles
5.2.1 Système de mesure du temps de montée et points de référence, si différents de 10 % à
5.2.2 Le graphique de la forme d’onde, si désiré.
5.2.3 Les valeurs crête à crête, si désirées.
Uniquement pour les mesures en fréquence
5.3.2 Les échelles du graphique, si autres que décibels (dB) et fréquence log.
5.3.3 Le choix éventuel d’un équipement de préférence.
5.3.4 Les résultats pour des valeurs discrètes de fréquence éventuelle Lorsqu’on préfère des valeurs au lieu d’un graphique, il est nécessaire de le préciser.
Scope and object
This part of IEC 60512 applies to interconnect assemblies, such as electrical connectors, sockets and cable assemblies.
This standard outlines test procedures to assess the electric and magnetic coupling between driven and quiet lines in an interconnect assembly It details both time domain (method A) and frequency domain (method B) approaches for single-ended and differential transmission, along with techniques for insertion and reference fixtures.
Definitions
For the purpose of this part of IEC 60512, the following definitions apply.
1.2.1 drive signal a step waveform (in the time domain) or a sinusoidal waveform (in the frequency domain)
The crosstalk ratio measures the amount of signal that is coupled into a quiet signal conductor or conductor pair compared to the signal magnitude in the driven conductor or conductor pair This ratio, which can be expressed in either percentage or decibels (dB), applies to signals measured in the same units, such as voltage or current.
The Near End Crosstalk Ratio (NEXT) is defined as the crosstalk ratio measured on a quiet line located at or near the sending end of a driven line It represents the relationship between the signal amplitude of the quiet line and the signal amplitude of the driven line at the near end.
The far end crosstalk ratio (FEXT) is defined as the crosstalk ratio measured on the quiet line near the receiving end of the driven line It represents the relationship between the signal amplitude of the quiet line at the far end and the signal amplitude of the driven line at the near end.
1.2.5 measurement system rise time rise time measured with fixture in place, without the specimen, and with filtering (or normal- ization) Rise time is typically measured from 10 % to 90 % levels
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The environmental impedance of the sample refers to the impedance presented by the setup to the signal conductors of the sample This impedance results from transmission lines, load resistances, connected signal sources and receivers, as well as disruptive mounting elements.
1.2.7 amplitude du front d’onde différence de potentiel entre les niveaux 0 % et 100 %, sans tenir compte des variations de part et d’autre, comme montré à la figure 1
The absolute standard setup serves as a reference without a test sample, featuring crosstalk characteristics identical to those of the test setup This configuration may or may not be part of the test board.
A wavefront generator is utilized for the emission line, while an oscilloscope monitors the induced line In differential applications, both devices must operate with differential signals, typically involving complementary outputs with adjustable amplitude and offset between the signals Additionally, there should be two inputs displaying both the sum and the difference Filtering and reshaping functions are necessary to modify the rise time Generally, a time-domain reflectometer (TDR) is employed for this purpose.
It is important to remind testing technicians of the limitations associated with all mathematical operations performed by an instrument, such as reshaping or filtering software.
Lorsque des sondes sont utilisées, elles doivent être adaptées en temps de montée et en caractéristiques de charge du circuit (résistance et capacité).
For optimal measurements, a network analyzer is preferred When a wider dynamic range is required, an alternative setup may include a signal generator paired with a spectrum analyzer or a vector network analyzer, especially for full two-port calibration measurements To enhance measurement sensitivity, additional equipment such as wideband output amplifiers or low-noise preamplifiers can be utilized Multi-port network analyzers and appropriate software, or baluns, are also effective for differential measurements.
Unless otherwise specified in the reference document, the sample's impedance in its environment must match the impedance of the testing equipment Typically, the impedance will be 50 Ω for asymmetric measurements and 100 Ω for differential measurements.
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The impedance presented to the specimen signal conductors by the fixture is influenced by various factors, including transmission lines, termination resistors, attached receivers or signal sources, and fixture parasitics.
1.2.7 step amplitude voltage difference between the 0 % and 100 % levels, ignoring overshoot and undershoot, as indicated in figure 1
1.2.8 isolation standard reference fixture without a test sample and with identical crosstalk characteristics as the test fixture This fixture may or may not be part of the test board
Equipment
Method A, time domain
2.1.1.1 A step generator is used on the driven line and an oscilloscope monitors the quiet line.
In differential applications, it is essential to process differential signals, which typically involves complementary outputs that allow for amplitude and skew adjustments Additionally, dual inputs should provide displays for both the difference and sum of the signals To accommodate varying rise times, filtering or normalization features are necessary, and a time domain reflectometer (TDR) is commonly utilized for these purposes.
NOTE The test professional should be aware of limitations of any mathematical operation(s) performed by an instrument, (e.g normalization or software filtering).
Probes, when used, shall have suitable rise time performance and circuit loading charac- teristics (resistance and capacitance).
Method B, frequency domain
For optimal measurements, a network analyzer is recommended, especially when a higher dynamic range is required Alternatively, a signal generator paired with a spectrum analyzer or a vector network analyzer can be utilized for comprehensive 2-port calibration To enhance measurement sensitivity, additional tools such as broadband output amplifiers or low-noise preamplifiers may be employed For differential measurements, a multi-port network analyzer equipped with suitable software or baluns is also an effective option.
Fixture
Specimen conductor assignments
For each measurement, ensure that the driven and quiet lines are fixtured as specified in the reference document In cases where the drive signal is differential and unbalanced, terminate the common mode energy Additionally, adjacent signal lines should be terminated to prevent resonance from electrically long lines, which can introduce errors Unless stated otherwise, maintain a 1:1 signal-to-ground ratio, using one differential pair for each ground when performing differential measurements, with all grounds connected at both ends Refer to figure A.4 for an example.
Termination
The driven lines' far end and both ends of the quiet line must be terminated in the specimen environment impedance, following the methods illustrated in figures A.2 and A.3.
Care should be taken to minimize the reactances of the resistive terminations over the range of test frequencies.
NOTE The fixture geometry and materials may impact the measurements due to the fixture parasitics Usually, the product's intended use dictates the most meaningful way to fixture it.
Crosstalk
Separating fixture crosstalk from specimen crosstalk is often challenging, as ground currents in fixture conductors can lead to common impedance coupling, increasing overall crosstalk To minimize the fixture's crosstalk contribution, the reference document must clearly specify the fixture and ensure that termination impedances are matched In the absence of such specifications, the fixture's contributions should remain relatively small compared to the crosstalk from the actual specimen.
To minimize crosstalk, it is essential to incorporate an isolation standard for measuring fixture crosstalk, as the test board footprint and cable assembly termination technique can greatly influence the results.
Insertion technique fixture
The fixture is designed to facilitate the measurement of crosstalk both with and without the specimen, as illustrated in figure A.1 It incorporates baluns for balanced measurements and minimum loss pads for impedance matching, as shown in figures A.2 and A.3.
Reference fixture technique
This technique employs a dedicated fixture that integrates both near end and far end for measuring fixture crosstalk The fixture is a replica of the specimen fixture, excluding the specimen itself It may incorporate traces that consist of fixture connectors, vias, bends, and corners Additionally, if baluns are utilized for balanced measurements or minimum loss pads for impedance matching, as illustrated in figures A.2 and A.3, these components are also part of the fixture.
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Pour cette procédure d’essai, l’échantillon à essayer doit avoir plus d’une ligne de signaux et doit être conforme à ce qui suit.
Une paire de connecteurs accouplés.
Des connecteurs et des câbles assemblés, et des connecteurs accouplés.
Une embase et un dispositif d’essai ou une embase et un adaptateur d’embase pour accouplement.
The far end of the emission lines and both ends of the induced lines must be loaded with the specified environmental impedance of the sample, utilizing one of the methods shown in Figures A.2 and A.3 To enhance accuracy, it may be necessary to load adjacent signal lines as well.
4.1.1 Disposer l’échantillon au minimum à 5 cm de tout objet susceptible d’affecter les résultats de mesure.
4.1.2 Mesure de référence et diaphonie du montage
Crosstalk is influenced by the rise time of the wavefront and the amplitude within the sample The rise time of the wavefront is extended by the setup, which is why the measured rise time of the system is always greater than that produced by the equipment and must be accurately measured The rise time should be assessed between the 10% and 90% levels.
The assembly introduces additional crosstalk to the sample's crosstalk It may include minimal loss circuits if utilized If the reference document accurately describes the assembly, its impact on crosstalk is understood, making the measurement of the assembly's crosstalk optional These results are presented in a graph of amplitude versus time Measurements of the rise time, emission amplitude, and assembly crosstalk are conducted using one of the following techniques.
Assemble the setup so that the near end is connected to the far end without the sample being in between, and connect the oscilloscope and pulse generator to the appropriate locations in the emission line setup For balanced measurements, adjust the amplitudes of the negative and positive fronts to be identical and disable the offset function between the generator signals, assuming the setup is designed for equal delays across all lines In the case of multiple emission lines operating simultaneously, ensure that the amplitudes are consistent and disable the offset function between the signals.
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For this test procedure, the test specimen shall have more than one signal line and shall be as follows.
Separable connectors
Cable assembly
Assembled connectors and cables, and mating connectors.
Sockets
A socket and test device or a socket and pluggable header adapter.
The driven lines' far end and the quiet line(s) ends must be terminated in the specimen environment impedance, following the methods illustrated in figures A.2 and A.3.
For increased accuracy, it may be necessary to terminate the adjacent signal lines.
Method A, time domain
4.1.1 Place the specimen a minimum of 5 cm from any objects that would affect measured results.
4.1.2 Reference measurement and fixture crosstalk
Crosstalk is influenced by the drive step rise time and amplitude of the specimen The fixture increases the drive step rise time, resulting in a measurement system rise time that exceeds that of the test equipment Therefore, it is essential to measure the rise time, which should be assessed from the 10% to 90% levels.
Fixture crosstalk contributes to overall specimen crosstalk, and the use of minimum loss pads in the fixture can influence this If the reference document clearly outlines the fixture's characteristics, measuring fixture crosstalk becomes optional The results are presented as a magnitude versus time plot, and it is essential to measure the system's rise time, drive amplitude, and fixture crosstalk using one of the specified techniques.
Assemble the fixture by connecting the near end to the far end without the specimen in between, and ensure the oscilloscope and pulse generator are properly connected to the driven line fixture For accurate balanced measurements, equalize the amplitudes of positive and negative steps and eliminate any skew at the signal source, assuming the fixture is designed with equal delays across all lines When dealing with multiple simultaneously driven lines, it is essential to match amplitudes and remove skew for optimal results.
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If the number of emission lines to be excited simultaneously exceeds the equipment's capabilities or if the elimination of offsets between channel signals is necessary, the lines can be activated one at a time, and the crosstalk can be calculated through superposition.
NOTE Cela peut ne pas être adapté pour les mesures de télédiaphonie des câbles longs.
Measure the rise time of the wavefront and the amplitude of the transmitted emission signal through the setup alone If necessary, this can be performed using the setup with the sample Adjust the filter (or reshaping) so that the measured rise time matches the required value or a value from Table 1.
Connect the oscilloscope to the specified location on the induced line as indicated in the reference document Measure the crosstalk amplitude of the setup with the sample removed Calculate the crosstalk rate by dividing the crosstalk amplitude by the wavefront amplitude and express it as a percentage Unless stated otherwise, record the peak values and their signs.
4.1.2.2 Technique du montage de référence
To connect the oscilloscope and pulse generator correctly in the emission line, ensure that the negative and positive pulse amplitudes are set to be equal for balanced measurements Additionally, disable the offset function between the signals of the generator.
(cela prộsume que le montage a ộtộ conỗu pour des retards identiques sur toutes les lignes).
Dans le cas de plusieurs lignes d’émission en simultané, faire en sorte que les amplitudes soient les mêmes et désactiver la fonction décalage entre les signaux.
If the number of emission lines to be excited simultaneously exceeds the equipment's capabilities or if the suppression of offsets between channel signals is a concern, the lines can be activated one at a time, and the crosstalk can be calculated through superposition.
Measure the rise time of the wavefront and the amplitude of the transmitted emission signal through the setup alone (If required for telephony, this can be done using the setup with the sample.) Adjust the filter (or reshaping) so that the measured rise time matches the required value or a value from Table 1.
Tableau 1 – Temps de montée recommandés du système de mesure
Temps de montée du signal préconisé pour l’application ps
Temps de montée du système de mesure ps
Connect the oscilloscope to the induced line location of the reference setup as specified in the reference document Measure the amplitude of the crosstalk in the setup Calculate the crosstalk rate by dividing the amplitude of the crosstalk by the amplitude of the wavefront and express it as a percentage Unless stated otherwise, record the peak values and their signs.
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When the simultaneous driving of lines surpasses the equipment's capacity or when addressing channel skew elimination is critical, it is advisable to drive the lines individually and calculate the crosstalk using superposition.
NOTE This may not be suitable for far end crosstalk measurements of long cable assemblies.
Measure the step rise time and amplitude of the drive signal transmitted solely through the fixture If needed, this measurement can also be performed using the fixture with the specimen Adjust the filtering or normalization to ensure that the measured rise time aligns with the requested value or a value from Table 1.
To measure fixture crosstalk amplitude, connect the oscilloscope to the designated quiet line location as outlined in the reference document With the specimen removed, calculate the fixture crosstalk ratio by dividing the measured crosstalk amplitude by the step amplitude, then express the result as a percentage Record the peak values and their signs unless otherwise instructed.
To ensure accurate measurements, connect the oscilloscope and pulse generator to the designated points on the driven line For balanced readings, ensure that the positive and negative steps have equal amplitudes and eliminate any skew at the signal source, assuming the fixture is designed with equal delays across all lines When dealing with multiple simultaneously driven lines, it is essential to match the amplitudes and remove any skew.
When the simultaneous driving of lines surpasses the equipment's capacity or when addressing channel skew elimination is critical, it is advisable to drive the lines individually and calculate the crosstalk using superposition.
Method B, frequency domain
4.2.1 Place the specimen a minimum of 5 cm from any objects that would affect measured results.
4.2.2 Calibration (reference measurement) and measurement of fixture crosstalk
Baluns utilized for balanced measurements and minimum loss pads for impedance matching, as illustrated in figures A.2 and A.3, are categorized under the term "fixture." When the reference document defines the fixture with a known crosstalk contribution, measuring the fixture's crosstalk becomes optional.
All measurement results must include at least 200 frequency points unless stated otherwise It is recommended to create a magnitude versus frequency plot with a vertical scale of 10 dB per division and to use a logarithmic frequency sweep Additionally, single frequency results should be presented in a table, as outlined in the reference document.
Assemble the fixture by connecting the near end to the far end without placing the specimen in between Connect the network analyzer ports to the designated locations on the driven line fixture and conduct a "through" calibration If the reference document indicates that measurements should be referenced to the output of the driven line instead of the input, ensure to perform this calibration with the specimen installed in the fixture.
Connect the receiver port to the quiet line location required in the reference document.
Measure the fixture crosstalk ratio in decibels (dB) without the specimen.
NOTE Unless specified by the reference document, a full 2-port calibration should not be performed because calibration standards cannot be attached to the fixture.
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Assemble the setup so that the near end is connected to the far end without placing the sample in between Connect the signal generator and the spectrum analyzer to the appropriate locations in the emission line setup Measure the reference.
Lorsque cela est requis, le signal de référence peut être mesuré à l’extrémité lointaine de l’échantillon, l’échantillon étant inclus dans la mesure.
Without altering any equipment settings, connect the spectrum analyzer to the induced line at the specified locations in the reference document Measure the crosstalk of the setup in dBm without the sample Subtract the reference measurement (in dBm) from these results to obtain the crosstalk of the setup in dB.
4.2.2.2 Technique du montage de référence
Create a reference setup with a missing function that is otherwise identical, incorporating both the near and far ends Connect the network analyzer, signal generator, or spectrum analyzer to the appropriate points in the emission line setup Perform a through calibration using the network analyzer or conduct a reference measurement with the signal generator and spectrum analyzer Connect the receiving port of the network analyzer or spectrum analyzer to the induced line of the reference setup as indicated in the reference document Measure the crosstalk of the setup in dB (for the network analyzer) or in dBm (for the spectrum analyzer) without the sample To obtain the crosstalk rate of the setup with a spectrum analyzer, divide this by the reference measurement.
4.2.3 Mesure de la diaphonie de l’échantillon
4.2.3.2 Connecter le signal d’entrée à la ligne d’émission et le port de réception de l’analyseur de réseau ou de l’analyseur de spectre de la ligne induite aux endroits requis.
To record crosstalk in decibels (dB), use a network analyzer to obtain the crosstalk rate If a spectrum analyzer is employed, divide the sample measurement by the reference measurement, as outlined in section 4.2.2 The resulting crosstalk rate should be plotted on a graph of amplitude versus frequency Additionally, document the results at discrete frequency values if requested.
When comparing this measurement to the crosstalk measured in sections 4.2.2.1 or 4.2.2.2, it is essential that the measured crosstalk is at least 20 dB higher than that of the assembly across all frequencies Any results that do not meet this requirement must be appropriately reported.
When interpreting results, it is crucial to exercise caution if the electrical length of the setup exceeds 1/8 of the wavelength of the highest test frequency, unless specific measures have been implemented to ensure proper impedance matching throughout the measurement path This can be verified by conducting a broad frequency sweep to check for null values caused by mode resonances, mounting issues, or symmetry problems.
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Assemble the fixture by connecting the near end to the far end without placing the specimen in between Connect the signal generator and spectrum analyzer to the designated points on the driven line fixture, and measure the reference signal If needed, the reference signal can also be measured at the far end of the specimen by including it in the measurement.
Connect the spectrum analyzer to the specified quiet line location without altering any equipment settings Measure the fixture crosstalk in dBm without the specimen present To obtain the fixture crosstalk in dB, subtract the reference measurement from these results.
To construct a reference fixture that lacks a specimen provision but remains otherwise identical, combine both the near and far ends Connect the network analyzer ports or the signal generator and spectrum analyzer to the appropriate locations on the driven line fixture Conduct a "through" calibration with the network analyzer or perform a reference measurement using the signal generator and spectrum analyzer, as needed with the specimen fixture Next, connect the receiver port of the network analyzer or spectrum analyzer to the quiet line location of the reference fixture as specified in the reference document Measure the fixture crosstalk ratio in decibels (dB) using the network analyzer or in dBm with the spectrum analyzer, ensuring to do this without the specimen To obtain the fixture crosstalk ratio with the spectrum analyzer, divide the measurement by the reference measurement.
4.2.3.2 Connect the signal source to the driven line and the receiver port of the network analyzer or the spectrum analyzer to the quiet line locations requested.
To record crosstalk in decibels (dB), utilize a network analyzer to determine the crosstalk ratio When employing a spectrum analyzer, calculate the crosstalk by dividing the specimen measurement by the reference measurement, as outlined in section 4.2.2 The final crosstalk ratio will be represented as a magnitude versus frequency plot.
Record single frequency results, if requested.
When comparing measurements, ensure that the crosstalk recorded in section 4.2.3.4 exceeds the fixture crosstalk values from sections 4.2.2.1 or 4.2.2.2 by at least 20 dB across all frequencies Any data that fails to meet this criterion must be clearly labeled.
When the electrical length of a fixture exceeds 1/8 wavelength at the highest test frequency, careful interpretation of the results is essential To ensure accurate impedance matching along the measurement path, special precautions should be implemented This can be verified by conducting a frequency sweep and monitoring for nulls caused by moding, fixture, or balun resonances.
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Les détails suivant doivent être spécifiés dans le document de référence.