320:
945:-1 variations included a high voltage differential (HVD) implementation whose maximum cable length was many times that of the single-ended version. SCSI equipment, for example, allows a maximum total cable length of 25 meters using HVD, while single-ended SCSI allows a maximum cable length of 1.5 to 6 meters, depending on bus speed. LVD versions of SCSI allow less than 25 m cable length not because of the lower voltage, but because these SCSI standards allow much higher speeds than the older HVD SCSI.
1266:
142:
890:, in which one conductor totally screens the other from the environment. All screens (or shields) are combined into a single piece of material to form a common ground. Differential signalling, however, is typically used with a balanced pair of conductors. For short cables and low frequencies, the two methods are equivalent, so cheap single-ended circuits with a common ground can be used with cheap cables. As signalling speeds become faster, wires begin to behave as transmission lines.
43:
670:
circuit in which both conductors and all circuits connected to them have the same impedance to ground and to all other conductors." Balanced interfaces were developed as a protection scheme against noise. In theory, it can reject any interference so long as it is common-mode (voltages that appear with equal magnitude and the same polarity in both conductors).
642:. This is twice the difference of the single-ended system. If the voltage noise on one wire is uncorrelated to the noise on the other one, it takes twice as much noise to cause an error with the differential system as with the single-ended system. In other words, differential signalling doubles the noise immunity.
331:, particularly in portable and mobile devices, continually strives to lower supply voltage to save power. A low supply voltage, however, reduces noise immunity. Differential signalling helps to reduce these problems because, for a given supply voltage, it provides twice the noise immunity of a single-ended system.
673:
There exists great confusion as to what constitutes a balanced interface and how it relates to differential signalling. In reality, they are two completely independent concepts: balanced interfacing concerns noise and interference rejection, while differential signalling only concerns headroom. The
245:
with differential receivers will reject noise regardless of whether the signal is differential or single-ended, but since balanced line noise rejection requires a differential receiver anyway, differential signalling is often used on balanced lines. Some of the benefits of differential signalling
669:
is a subsystem containing three parts: a driver, a line, and a receiver. These three components complete a full circuit for a signal to travel through and the impedances of this circuit is what determines whether the interface as a whole is balanced or not: "A balanced circuit is a two-conductor
910:
in computers, due to geometric constraints and the fact that screening does not work at DC. If a DC power supply line and a low-voltage signal line share the same ground, the power current returning through the ground can induce a significant voltage in it. A low-resistance ground reduces this
650:
In single-ended signalling, the transmitter generates a single voltage that the receiver compares with a fixed reference voltage, both relative to a common ground connection shared by both ends. In many instances, single-ended designs are not feasible. Another difficulty is the electromagnetic
915:
does. Because each line causes a matching image current in the ground plane, which is required anyway for supplying power, the pair looks like four lines and therefore has a shorter crosstalk distance than a simple isolated pair. In fact, it behaves as well as a twisted pair. Low crosstalk is
274:
At higher frequencies, the output impedance of the output amplifier can change, resulting in a small imbalance. When driven in differential mode by two identical amplifiers, this impedance change will be the same for both lines, and thus cancelled
1151:
Let's be clear from the start here: if the source impedance of each of these signals was not identical i.e. balanced, the method would fail completely, the matching of the differential audio signals being irrelevant, though desirable for headroom
1175:
Only the common-mode impedance balance of the driver, line, and receiver play a role in noise or interference rejection. This noise or interference rejection property is independent of the presence of a desired differential
574:
519:
439:
640:
1392:
467:
387:
359:
1363:
1097:
1127:
996:
in hardware development, to help to cope with common cabling errors through swapped wires, or easily fix common design errors under firmware control. Many
750:
1170:
746:
1298:
60:
1462:
989:
1242:
1234:
Modern
Computer Architecture and Organization: Learn x86, ARM, and RISC-V architectures and the design of smartphones, PCS, and cloud servers
911:
problem to some extent. A balanced pair of microstrip lines is a convenient solution because it does not need an additional PCB layer, as a
953:
323:
Differential amplifiers respond to differential signals by amplifying the difference between the voltages on the amplifier’s two inputs.
199:. The receiving circuit responds to the difference between the two signals, which results in a signal with a magnitude twice as large.
255:
107:
31:
737:
Differential pairs generally carry differential or semi-differential signals, such as high-speed digital serial interfaces including
126:
79:
441:. Now consider a differential system with the same supply voltage. The voltage difference in the high state, where one wire is at
886:
that connects two devices (chips, modules) often dictates the type of signalling. Single-ended signalling is typically used with
665:
When transmitting signals differentially between two pieces of equipment it is common to do so through a balanced interface. An
319:
1457:
161:
86:
1384:
1326:
64:
1330:
93:
899:
687:
265:
1355:
1258:
75:
758:
292:
524:
53:
1012:
472:
392:
1139:
762:
695:
651:
interference that can be generated by a single-ended signalling system that attempts to operate at high speed.
219:
579:
1452:
1092:
230:
1287:
1062:
968:, under firmware control, or even automatic) to swap the polarity of the two differential signals, called
993:
742:
731:
233:
which drives only one conductor with signal, while the other is connected to a fixed reference voltage.
181:
222:
when fed into a differential receiver. Differential signalling does not make a line balanced, nor does
1424:
1388:
1217:
1082:
801:
328:
169:
100:
250:
Doubled signal voltage between the differential pair (compared to a single-ended signal of the same
141:
1420:
1198:
864:
800:
Differential signalling often uses length-matched wires or conductors which are used in high speed
691:
223:
196:
1051:
699:
271:
Longer cable runs are possible due to this increased noise immunity and 6 dB extra headroom.
261:
1413:
1238:
883:
703:
521:. The voltage difference in the low state, where the voltages on the wires are exchanged, is
444:
364:
1087:
1067:
965:
660:
211:
674:
impedance balance of a circuit does not determine the signals it can carry and vice versa.
337:
964:
Some integrated circuits dealing with differential signals provide a hardware option (via
858:
812:
Data rates of some interfaces implemented with differential pairs include the following:
145:
A signal transmitted differentially. Notice the increased amplitude at the receiving end.
241:
Contrary to popular belief, differential signalling does not affect noise cancellation.
1021:
907:
822:
754:
717:
280:
192:
1446:
887:
251:
242:
215:
1123:
1045:
794:
713:
389:
and the low logic level is 0 V. The difference between the two levels is therefore
177:
173:
1319:
17:
1232:
30:
This article is about electric signals via wires. For an immunology concept, see
1072:
1003:
867:– 10 Gbit/s (four differential pairs running at 2.5 Gbit/s each)
834:
300:
296:
157:
153:
42:
956:(LVDS), on the other hand, is a specific system defined by a TIA/EIA standard.
1259:"Can I swap the positive (p) and negative (n) signals of a differential pair?"
1135:
916:
important when many lines are packed into a small space, as on a typical PCB.
903:
852:
840:
828:
816:
778:
723:
1077:
1057:
1040:
1028:
912:
870:
727:
683:
1291:
997:
932:
786:
203:
793:, etc., or else high quality and/or high frequency analog signals (e.g.
1427:. June 2005. Application Note 127, KS8001, M9999-060105, (408) 955-1690
928:
334:
To see why, consider a single-ended digital system with supply voltage
188:
873:– 3.2 Gbit/s (differential strobes latch single-ended data)
706:
or high-quality balanced line and balanced circuit audio signal path.
1294:
770:
766:
288:
284:
694:
emission and noise acceptance, and can achieve a constant or known
1262:
318:
140:
576:. The difference between high and low logic levels is therefore
226:
rejection in balanced circuits require differential signalling.
1017:
942:
846:
790:
782:
738:
304:
279:
Differential signalling works for both analog signalling, as in
1000:
774:
308:
36:
898:
Differential signalling is often used in computers to reduce
1320:"TUSB73x0 Board Design and Layout Guidelines - User's Guide"
1356:"Simplify Routing With Pin, Part, And Diff-Pair Swapping"
206:
signals of differential signalling may be referred to as
164:. The technique sends the same electrical signal as a
582:
527:
475:
447:
395:
367:
340:
1027:Another way to deal with polarity errors is to use
67:. Unsourced material may be challenged and removed.
988:. This can be utilized to simplify or improve the
902:, because complete screening is not possible with
634:
568:
513:
461:
433:
381:
353:
210:, but this term is more appropriately applied to
1214:Noise Reduction Techniques in Electronic Systems
315:Suitability for use with low-voltage electronics
268:) is easily rejected by a differential receiver.
264:noise between the two amps (e.g. from imperfect
27:Method for electrically transmitting information
1385:"Can the Ethernet transformer pairs be swapped"
1329:. February 2016 . Literature Number: SLLU149E.
229:Differential signalling is to be contrasted to
992:of high-speed differential pairs of traces on
8:
1118:
1116:
1114:
1098:Transition Minimized Differential Signalling
702:techniques important in a high-speed signal
569:{\displaystyle 0\,\mathrm {V} -V_{S}=-V_{S}}
514:{\displaystyle V_{S}-0\,\mathrm {V} =V_{S}}
434:{\displaystyle V_{S}-0\,\mathrm {V} =V_{S}}
172:. The pair of conductors can be wires in a
1288:"Understanding Lane Reversal and Polarity"
1188:
1186:
1184:
1173:. 2000. pp. 111–. IEC 602689-3:2001.
925:High-voltage differential (HVD) signalling
1414:"New Generation Ethernet PHY with LinkMD"
1171:International Electrotechnical Commission
631:
625:
606:
587:
581:
560:
544:
532:
531:
526:
505:
493:
492:
480:
474:
458:
452:
446:
425:
413:
412:
400:
394:
378:
372:
366:
345:
339:
127:Learn how and when to remove this message
730:differential pair routing techniques on
1231:Ledin, Jim; Farley, Dave (2022-05-04).
1169:(Third ed.). Geneva, Switzerland:
1110:
646:Comparison with single-ended signalling
635:{\displaystyle V_{S}-(-V_{S})=2V_{S}\,}
187:Electrically, the two conductors carry
1024:also support lane polarity inversion.
1008:auto polarity detection and correction
7:
950:high-voltage differential signalling
920:High-voltage differential signalling
65:adding citations to reliable sources
1010:(not to be confused with a similar
954:Low-voltage differential signalling
682:The technique minimizes electronic
283:, and in digital signalling, as in
533:
494:
414:
32:Differential signalling hypothesis
25:
797:, balanced audio signals, etc.).
952:describes a variety of systems.
939:normally means 5 volts or more.
861:– 5.0 Gbit/s per lane
41:
1395:from the original on 2020-08-09
1366:from the original on 2021-06-14
1336:from the original on 2021-05-06
1301:from the original on 2021-04-13
1269:from the original on 2022-02-25
1029:polarity-insensitive line codes
655:Relation to balanced interfaces
52:needs additional citations for
1463:Telecommunications engineering
1327:Texas Instruments Incorporated
612:
596:
1:
1419:. San Jose, California, USA:
1265:. 2012-09-11. ID: 000085787.
1195:Handbook for Sound Engineers
900:electromagnetic interference
709:Differential pairs include:
688:electromagnetic interference
168:of signals, each in its own
978:differential pair inversion
191:signals which are equal in
1479:
970:differential pair swapping
759:Ethernet over twisted pair
678:Uses of differential pairs
658:
361:. The high logic level is
293:Ethernet over twisted pair
254:), giving 6 dB extra
29:
1193:Ballou, Glenn M. (2015).
849:– 3.125 Gbit/s
469:and the other at 0 V, is
76:"Differential signalling"
1128:"Audio Balancing Issues"
763:serial digital interface
696:characteristic impedance
220:common-mode interference
160:using two complementary
1362:. Altium. 2020-10-27 .
1093:Single-ended signalling
853:Serial ATA Revision 3.0
843:– 2.4 Gbit/s
841:Serial ATA Revision 2.0
837:– 2.5 Gbit/s
831:– 2.5 Gbit/s
825:– 1.6 Gbit/s
819:– 1.5 Gbit/s
462:{\displaystyle V_{S}\,}
382:{\displaystyle V_{S}\,}
231:single-ended signalling
150:Differential signalling
1458:Communication circuits
1212:Ott, Henry W. (1988).
1167:Sound system equipment
1165:"Part 3: Amplifiers".
1063:Differential amplifier
994:printed circuit boards
732:printed circuit boards
636:
570:
515:
463:
435:
383:
355:
324:
266:power supply rejection
146:
1218:John Wiley & Sons
1201:. pp. 1267–1268.
855:– 6 Gbit/s
637:
571:
516:
464:
436:
384:
356:
354:{\displaystyle V_{S}}
322:
182:printed circuit board
144:
1425:Microchip Technology
1389:Microchip Technology
1237:. Packt Publishing.
1199:Taylor & Francis
1083:Longitudinal voltage
580:
525:
473:
445:
393:
365:
338:
329:electronics industry
61:improve this article
1421:Micrel Incorporated
1261:. Troubleshooting.
1216:(Second ed.).
865:10 Gigabit Ethernet
1197:(Fifth ed.).
1052:Current mode logic
982:polarity inversion
974:polarity reversion
960:Polarity switching
878:Transmission lines
808:Data rate examples
700:impedance matching
632:
566:
511:
459:
431:
379:
351:
325:
195:, but of opposite
147:
18:Differential input
1244:978-1-80323-823-4
966:strapping options
948:The generic term
884:transmission line
704:transmission line
212:balanced circuits
166:differential pair
137:
136:
129:
111:
16:(Redirected from
1470:
1437:
1435:
1433:
1432:
1418:
1410:
1404:
1403:
1401:
1400:
1381:
1375:
1374:
1372:
1371:
1352:
1346:
1344:
1342:
1341:
1335:
1324:
1316:
1310:
1309:
1307:
1306:
1284:
1278:
1277:
1275:
1274:
1255:
1249:
1248:
1228:
1222:
1221:
1209:
1203:
1202:
1190:
1179:
1178:
1162:
1156:
1154:
1148:
1147:
1138:. Archived from
1120:
1088:Signal integrity
1068:Differential TTL
1006:support this as
894:Use in computers
661:Balanced circuit
641:
639:
638:
633:
630:
629:
611:
610:
592:
591:
575:
573:
572:
567:
565:
564:
549:
548:
536:
520:
518:
517:
512:
510:
509:
497:
485:
484:
468:
466:
465:
460:
457:
456:
440:
438:
437:
432:
430:
429:
417:
405:
404:
388:
386:
385:
380:
377:
376:
360:
358:
357:
352:
350:
349:
152:is a method for
132:
125:
121:
118:
112:
110:
69:
45:
37:
21:
1478:
1477:
1473:
1472:
1471:
1469:
1468:
1467:
1443:
1442:
1441:
1440:
1430:
1428:
1416:
1412:
1411:
1407:
1398:
1396:
1383:
1382:
1378:
1369:
1367:
1354:
1353:
1349:
1339:
1337:
1333:
1322:
1318:
1317:
1313:
1304:
1302:
1286:
1285:
1281:
1272:
1270:
1257:
1256:
1252:
1245:
1230:
1229:
1225:
1211:
1210:
1206:
1192:
1191:
1182:
1164:
1163:
1159:
1152:considerations.
1145:
1143:
1122:
1121:
1112:
1107:
1037:
962:
922:
896:
880:
859:PCI Express 2.0
810:
680:
663:
657:
648:
621:
602:
583:
578:
577:
556:
540:
523:
522:
501:
476:
471:
470:
448:
443:
442:
421:
396:
391:
390:
368:
363:
362:
341:
336:
335:
317:
239:
180:or traces on a
133:
122:
116:
113:
70:
68:
58:
46:
35:
28:
23:
22:
15:
12:
11:
5:
1476:
1474:
1466:
1465:
1460:
1455:
1453:Computer buses
1445:
1444:
1439:
1438:
1405:
1391:. 2020-03-03.
1376:
1347:
1311:
1297:. 2013-01-09.
1279:
1250:
1243:
1223:
1220:. p. 116.
1204:
1180:
1157:
1109:
1108:
1106:
1103:
1102:
1101:
1095:
1090:
1085:
1080:
1075:
1070:
1065:
1060:
1055:
1049:
1043:
1036:
1033:
1022:USB SuperSpeed
1013:auto crossover
986:lane inversion
961:
958:
921:
918:
895:
892:
888:coaxial cables
879:
876:
875:
874:
868:
862:
856:
850:
844:
838:
832:
826:
823:Hypertransport
820:
809:
806:
755:Hypertransport
735:
734:
721:
720:and unshielded
679:
676:
659:Main article:
656:
653:
647:
644:
628:
624:
620:
617:
614:
609:
605:
601:
598:
595:
590:
586:
563:
559:
555:
552:
547:
543:
539:
535:
530:
508:
504:
500:
496:
491:
488:
483:
479:
455:
451:
428:
424:
420:
416:
411:
408:
403:
399:
375:
371:
348:
344:
316:
313:
281:balanced audio
277:
276:
272:
269:
259:
243:Balanced lines
238:
235:
216:balanced lines
135:
134:
49:
47:
40:
26:
24:
14:
13:
10:
9:
6:
4:
3:
2:
1475:
1464:
1461:
1459:
1456:
1454:
1451:
1450:
1448:
1426:
1422:
1415:
1409:
1406:
1394:
1390:
1387:. Knowledge.
1386:
1380:
1377:
1365:
1361:
1357:
1351:
1348:
1332:
1328:
1321:
1315:
1312:
1300:
1296:
1293:
1289:
1283:
1280:
1268:
1264:
1260:
1254:
1251:
1246:
1240:
1236:
1235:
1227:
1224:
1219:
1215:
1208:
1205:
1200:
1196:
1189:
1187:
1185:
1181:
1177:
1172:
1168:
1161:
1158:
1153:
1142:on 2010-07-31
1141:
1137:
1133:
1129:
1125:
1124:Blyth, Graham
1119:
1117:
1115:
1111:
1104:
1099:
1096:
1094:
1091:
1089:
1086:
1084:
1081:
1079:
1076:
1074:
1071:
1069:
1066:
1064:
1061:
1059:
1056:
1053:
1050:
1047:
1044:
1042:
1039:
1038:
1034:
1032:
1030:
1025:
1023:
1019:
1015:
1014:
1009:
1005:
1002:
999:
995:
991:
987:
983:
979:
975:
971:
967:
959:
957:
955:
951:
946:
944:
940:
938:
935:electronics,
934:
930:
926:
919:
917:
914:
909:
905:
901:
893:
891:
889:
885:
877:
872:
869:
866:
863:
860:
857:
854:
851:
848:
845:
842:
839:
836:
833:
830:
827:
824:
821:
818:
815:
814:
813:
807:
805:
803:
798:
796:
795:video signals
792:
788:
784:
780:
776:
772:
768:
764:
760:
756:
752:
748:
744:
741:differential
740:
733:
729:
725:
722:
719:
715:
712:
711:
710:
707:
705:
701:
697:
693:
689:
685:
677:
675:
671:
668:
662:
654:
652:
645:
643:
626:
622:
618:
615:
607:
603:
599:
593:
588:
584:
561:
557:
553:
550:
545:
541:
537:
528:
506:
502:
498:
489:
486:
481:
477:
453:
449:
426:
422:
418:
409:
406:
401:
397:
373:
369:
346:
342:
332:
330:
321:
314:
312:
310:
306:
302:
298:
294:
290:
286:
282:
273:
270:
267:
263:
260:
257:
253:
252:nominal level
249:
248:
247:
244:
236:
234:
232:
227:
225:
221:
218:which reject
217:
213:
209:
205:
200:
198:
194:
190:
185:
183:
179:
175:
171:
167:
163:
159:
156:transmitting
155:
151:
143:
139:
131:
128:
120:
109:
106:
102:
99:
95:
92:
88:
85:
81:
78: –
77:
73:
72:Find sources:
66:
62:
56:
55:
50:This article
48:
44:
39:
38:
33:
19:
1429:. Retrieved
1408:
1397:. Retrieved
1379:
1368:. Retrieved
1360:White Papers
1359:
1350:
1338:. Retrieved
1314:
1303:. Retrieved
1282:
1271:. Retrieved
1253:
1233:
1226:
1213:
1207:
1194:
1174:
1166:
1160:
1150:
1144:. Retrieved
1140:the original
1132:White Papers
1131:
1046:Current loop
1026:
1011:
1007:
1004:transceivers
985:
981:
977:
973:
969:
963:
949:
947:
941:
937:high voltage
936:
931:signals. In
924:
923:
897:
882:The type of
881:
811:
802:serial links
799:
736:
714:Twisted-pair
708:
681:
672:
666:
664:
649:
333:
326:
278:
240:
228:
207:
201:
186:
178:ribbon cable
174:twisted-pair
165:
154:electrically
149:
148:
138:
123:
117:January 2021
114:
104:
97:
90:
83:
71:
59:Please help
54:verification
51:
1073:DisplayPort
904:microstrips
835:PCI Express
698:, allowing
301:DisplayPort
297:PCI Express
262:Common-mode
204:symmetrical
158:information
1447:Categories
1431:2022-02-25
1399:2022-02-25
1370:2022-02-25
1345:(45 pages)
1340:2022-02-25
1305:2022-02-25
1273:2022-02-25
1146:2010-12-30
1136:Soundcraft
1105:References
1048:signalling
1041:Backplanes
1016:feature).
927:uses high-
829:Infiniband
817:Serial ATA
779:Serial ATA
724:Microstrip
237:Advantages
87:newspapers
1436:(5 pages)
1155:(3 pages)
1078:Humbucker
1058:DDR SDRAM
913:stripline
871:DDR SDRAM
728:stripline
684:crosstalk
667:interface
600:−
594:−
554:−
538:−
487:−
407:−
246:include:
193:magnitude
170:conductor
1393:Archived
1364:Archived
1331:Archived
1299:Archived
1292:Teledyne
1267:Archived
1126:(2009).
1035:See also
998:Ethernet
933:computer
787:FireWire
718:shielded
716:cables,
256:headroom
208:balanced
197:polarity
1176:signal.
990:routing
929:voltage
690:, both
189:voltage
162:signals
101:scholar
1295:LeCroy
1241:
1100:(TMDS)
789:, and
771:RS-485
767:RS-422
751:LVPECL
289:RS-485
285:RS-422
103:
96:
89:
82:
74:
1417:(PDF)
1334:(PDF)
1323:(PDF)
1263:Intel
1054:(CML)
984:, or
908:chips
692:noise
224:noise
108:JSTOR
94:books
1239:ISBN
1020:and
1018:PCIe
943:SCSI
906:and
847:XAUI
791:HDMI
783:TMDS
747:PECL
739:LVDS
726:and
686:and
327:The
307:and
305:HDMI
275:out.
214:and
202:The
80:news
1001:PHY
775:USB
743:ECL
309:USB
184:.
176:or
63:by
1449::
1423:/
1358:.
1325:.
1290:.
1183:^
1149:.
1134:.
1130:.
1113:^
1031:.
980:,
976:,
972:,
804:.
785:,
781:,
777:,
773:,
769:,
765:,
761:,
757:,
753:,
749:,
745:,
311:.
303:,
299:,
295:,
291:,
287:,
1434:.
1402:.
1373:.
1343:.
1308:.
1276:.
1247:.
627:S
623:V
619:2
616:=
613:)
608:S
604:V
597:(
589:S
585:V
562:S
558:V
551:=
546:S
542:V
534:V
529:0
507:S
503:V
499:=
495:V
490:0
482:S
478:V
454:S
450:V
427:S
423:V
419:=
415:V
410:0
402:S
398:V
374:S
370:V
347:S
343:V
258:.
130:)
124:(
119:)
115:(
105:·
98:·
91:·
84:·
57:.
34:.
20:)
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
