1、 EIA STANDARD TP-90 Crosstalk Ratio Test Procedure for Electrical Connectors, Sockets, Cable Assemblies or Interconnection Systems EIA-364-90 January 2000 EIA-364-90 ANSI/EIA-364-90-2000 (R2013) Approved: January 13, 2000 Reaffirmed: January 28, 2013 NOTICE EIA Engineering Standards and Publications
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4、r than ECIA members, whether the standard is to be used either domestically or internationally. Standards and Publications are adopted by ECIA in accordance with the American National Standards Institute (ANSI) patent policy. By such action, ECIA does not assume any liability to any patent owner, no
5、r does it assume any obligation whatever to parties adopting the Standard or Publication. This EIA Standard is considered to have International Standardization implication, but the International Electrotechnical Commission activity has not progressed to the point where a valid comparison between the
6、 EIA Standard and the IEC document can be made. This Standard does not purport to address all safety problems associated with its use or all applicable regulatory requirements. It is the responsibility of the user of this Standard to establish appropriate safety and health practices and to determine
7、 the applicability of regulatory limitations before its use. Created under Standards Proposal No. 3404 and reaffirmed under Standards Proposal No. 5253.04 under the cognizance of the CE-2.0 Committee on EIA National Connector and Socket Standards). Published by Electronic Components Industry Associa
8、tion 2013 Engineering Department 2214 Rock Hill Road, Suite 170 Herndon, VA 20170 PLEASE! DONT VIOLATE THE LAW! This document is copyrighted by the ECIA and may not be reproduced without permission. Organizations may obtain permission to reproduce a limited number of copies through entering into a l
9、icense agreement. For information, contact: IHS 15 Inverness Way East Englewood, CO 80112-5704 or call USA and Canada (1-877-413-5184), International (303-397-7956) i Clause 1 CONTENTS Introduction Page11.1 Scope 11.2 Object . 11.3 Definitions 12 Test resources . 22.1 Equipment 22.2 Fixture 33 Test
10、specimen . 43.1 Description . 44 Test procedure 54.1 Method A, time domain . 54.1.1 General . 54.1.2 Insertion technique . 54.1.3 Reference fixture technique 64.1.4 Specimen crosstalk measurement . 64.2 Method B, frequency domain . 74.2.1 General . 74.2.2 Insertion technique . 74.2.3 Reference fixtu
11、re technique 84.2.4 Specimen crosstalk measurement . 95 Details to be specified 95.1 All tests . 95.2 Time domain only 105.3 Frequency domain only 106 Test documentation 11ii CONTENTS (continued) Table Page 1 Recommended measurement system rise time (including fixture and filtering) 6 Figure 1 Wavef
12、orm . 11 A.1 Technique diagram . A-1 A.2 Single-ended terminations A-2 A.3 Differential (balanced) terminations A-3 A.4 Example of far end crosstalk with balanced terminations see figure A.3.a (2nd) and figure A.3.b for Zo = 100 A-4 Annex A Normative . A-1 B Informative . B-1 EIA-364-90 Page 1 TEST
13、PROCEDURE No. 90 CROSSTALK RATIO TEST PROCEDURE FOR ELECTRICAL CONNECTORS, SOCKETS, CABLE ASSEMBLIES OR INTERCONNECT SYSTEMS (From EIA Standards Proposal No. 3404, formulated under the cognizance EIA CE-2.0 Committee on National Connector Standards) 1 Introduction 1.1 Scope This procedure applies to
14、 interconnect assemblies, such as electrical connectors, sockets and cable assemblies. 1.2 Object This standard describes test methods for measuring the magnitude of the electromagnetic coupling between driven and quiet lines of an interconnect assembly. Both time domain (method A) and frequency dom
15、ain methods (method B), single-ended and differential transmission, and insertion and reference fixture techniques are described. 1.3 Definitions 1.3.1 Drive signal For the time domain method, the drive signal is a step waveform. For the frequency domain method, the drive signal is sinusoidal. 1.3.2
16、 Crosstalk ratio The ratio of the signal coupled (induced) into the quiet signal conductor or conductor pair to the magnitude of the signal in the driven conductor or conductor pair. Both signals shall have the same units of either voltage or current, and the ratio may be expressed as percent or dB.
17、 1.3.3 Near end crosstalk ratio (NEXT) The crosstalk ratio calculated on the quiet line at or in proximity to the sending (signal source) end of the driven line. This is the ratio of the near end quiet line signal amplitude to the near end driven line signal amplitude. EIA-364-90 Page 2 1.3.4 Far en
18、d crosstalk ratio (FEXT) The crosstalk ratio calculated on the quiet line at or in proximity to the receiving (destination) end of the driven line. This is the ratio of the far end quiet line signal amplitude to the near end driven line signal amplitude. 1.3.5 Measurement system rise time Rise time
19、measured with fixture in place, without the specimen, and with filtering (or normalization). Rise time is typically measured from 10% to 90% levels. 1.3.6 Specimen environment impedance The impedance presented to the specimen signal conductors by the fixture. This impedance is a result of transmissi
20、on lines, termination resistors, attached receivers or signal sources, and fixture parasitics. 1.3.7 Step amplitude The voltage difference between the 0% and 100% levels, ignoring overshoot and undershoot, as indicated in figure 1. 1.3.8 Isolation standard A reference fixture without a test specimen
21、 and with identical crosstalk characteristics as the test fixture. This fixture may or may not be part of the test board. 1.3.9 Termination (electronics usage) An impedance connected to the end of a transmission line, typically to minimize reflected energy on the line. 2 Test resources 2.1 Equipment
22、 2.1.1 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 a differential application both shall be able to process differential signals. Typically, this means complementary outputs with provision for amplitude and skew adjustment
23、, and dual inputs with a display of the difference and sum. Filtering or normalization shall be available for varying the rise time. A time domain reflectometer (TDR) is usually used. EIA-364-90 Page 3 NOTE - The test professional should be aware of limitations of any math operation(s) performed by
24、an instrument, (e.g. normalization or software filtering). 2.1.1.2 Probes Probes, when used, shall have suitable rise time performance and circuit loading characteristics (e.g. resistance and capacitance). 2.1.2 Method B, frequency domain A network analyzer is preferred. When greater dynamic range i
25、s desired, a signal generator and spectrum analyzer may alternatively be used. An 8 port network analyzer or baluns may be used for differential measurements. 2.2 Fixture Unless otherwise specified in the referencing document the specimen environment impedance shall match the impedance of the test e
26、quipment. Typically this will be 50 ohms for single-ended measurements and 100 ohms for differential. 2.2.1 Specimen conductor assignments For each measurement, the driven and quiet lines shall be fixtured as indicated in the referencing document. Adjacent signal lines to these should likewise be te
27、rminated if possible (electrically long adjacent signal lines may resonate adding error to the results). Unless otherwise specified a 1:1 signal to ground ratio (one differential pair to one ground if differential measurements are performed) shall be used with each end having all grounds commoned, f
28、or an example, see figure A.4. The fixture should be designed with equal delays for all lines. NOTE When the drive signal is differential and not balanced, the common mode energy shall be terminated. 2.2.2 Termination The far end of the driven lines and both ends of the quiet line shall be terminate
29、d in the specimen environment impedance specified using one of the methods in figures A.2 and A.3. Matching networks may be used if the specimen environment impedance does not match that of the test equipment. Care should be taken to minimize the reactances of the resistive terminations over the ran
30、ge of test frequencies. NOTE The fixture geometry and materials may impact the measurements due to the fixture parasitics. Usually the products intended use dictates the most meaningful way to fixture it. EIA-364-90 Page 4 2.2.3 Crosstalk It may be difficult to separate fixture crosstalk from that o
31、f the specimen. The referencing document should specify the fixture so that its crosstalk contribution is minimized. NOTE 1 Since the test board footprint or cable assembly termination technique can significantly impact the crosstalk it is recommended that an isolation standard (for measuring fixtur
32、e crosstalk) be included in the fixture. 2.2.4 Insertion technique fixture The fixture shall be designed to allow measurement of crosstalk with and without the specimen, see figure A.1. If baluns are used for a balanced measurement, or minimum loss pads used for impedance matching; see figures A2 an
33、d A.3, these are included in the fixture. 2.2.5 Reference fixture technique In this technique a separate fixture that combines both near end and far end is used for the fixture crosstalk measurement. This fixture shall be a duplicate of the specimen fixture, only without the specimen. Traces, if use
34、d, shall include fixture connectors, vias, bends and corners. If baluns are used for a balanced measurement, or minimum loss pads used for impedance matching; see figures A.2 and A.3, these are included in the fixture. 3 Test specimen 3.1 Description For this test procedure the test specimen shall h
35、ave more than one signal line and shall be one of the following: 3.1.1 Separable connectors A mated connector pair. 3.1.2 Cable assembly Assembled connectors and cables, and mating connectors. 3.1.3 Sockets A socket and test device or a socket and pluggable header adapter. EIA-364-90 Page 5 4 Test p
36、rocedure The far end of the driven lines and both ends of the quiet line(s) shall be terminated in the specimen environment impedance specified using one of the methods in figures A.2 and A.3. 4.1 Method A, time domain 4.1.1 General 4.1.1.1 Place the specimen a minimum of 5 cm from any objects that
37、would affect measured results. 4.1.1.2 Reference measurement and fixture crosstalk 4.1.1.2.1 Measure and record the measurement system rise time from 10% to 90% levels, unless otherwise specified in the referencing document. 4.1.1.2.2 Fixture crosstalk contributes to the specimen crosstalk. The fixt
38、ure includes minimum loss pads, if used. If the referencing document precisely describes the fixture so that its crosstalk contribution is known, then the fixture crosstalk measurement is optional. These results are a magnitude versus time plot. Measure the measurement system rise time, drive amplit
39、ude and fixture crosstalk with one of the following techniques. 4.1.2 Insertion technique 4.1.2.1 Assemble the fixture so that the near end is connected to the far end without the specimen in between, and connect the oscilloscope and pulse generator to the appropriate locations of the driven line fi
40、xture. For multiple simultaneously driven lines, match amplitudes and minimize the skew between lines, and if balanced, minimize skew within the pair. Measure and report the skew values. 4.1.2.2 If the number of lines to be driven simultaneously exceeds the equipment capability or channel skew elimi
41、nation is a concern, the lines may be driven one at a time and the crosstalk calculated by superposition. 4.1.2.3 Measure the step rise time and amplitude of the drive signal transmitted through the fixture alone. (If requested this can be done using the fixture with specimen.) Adjust the filtering
42、(or normalization) so the measured rise time matches the value requested, or a value from table 1. 4.1.2.4 Connect the oscilloscope to the quiet line location as specified in the referencing document. Measure the fixture crosstalk amplitude with the specimen removed. Calculate the fixture crosstalk
43、ratio by dividing the fixture crosstalk amplitude by the step amplitude and express as a percent. Unless otherwise specified record the peak values and the sign. EIA-364-90 Page 6 4.1.3 Reference fixture technique 4.1.3.1 Connect the oscilloscope and pulse generator to the appropriate locations of t
44、he driven line. For balanced measurements, make positive and negative steps equal in amplitude and remove skew at the signal source, (this assumes that the fixture has been designed with equal delays between all lines). For multiple simultaneously driven lines, match amplitudes and remove skew. 4.1.
45、3.2 If the number of lines to be driven simultaneously exceeds the equipment capability or channel skew elimination is a concern, the lines may be driven one at a time and the crosstalk calculated by superposition. 4.1.3.3 Measure the step rise time and amplitude of the drive signal transmitted thro
46、ugh the reference fixture. (If requested for FEXT do this using the fixture with specimen). Adjust the filtering (or normalization) so the measured rise time matches the value requested, or a value from table 1. Table 1 - Recommended measurement system rise time (including fixture and filtering) Exp
47、ected application signal rise time, picoseconds Measurement system rise time, picoseconds 100 500 100 500 - 1,000 500 1,000 1000 4.1.3.4 Connect the oscilloscope to the quiet line location of the reference fixture specified in the referencing document. Measure the amplitude of the quiet line signal
48、at its maximum excursion. Subtract from this value the amplitude of the quiet line signal prior to the time of the edge of the driven line signal to obtain the quiet line crosstalk value (maintaining the sign). Calculate the fixture crosstalk ratio by dividing the quiet line crosstalk value by the s
49、tep amplitude and express as a percent. 4.1.4 Specimen crosstalk measurement 4.1.4.1 Add specimen to fixture. 4.1.4.2 Connect the oscilloscope to the quiet line and the step generator to the driven line at the locations requested. For balanced measurements, make positive and negative steps equal in amplitude and remove skew at the signal source, (this assumes that the fixture has been designed with equal delays between all lines). For multiple simultaneously driven lines, match amplitudes and remove skew. EIA-364-90 Page 7 4.1.4.3 If the number of lines to be driven
