High speed modular jack

Details High speed modular jack High speed modular jack

2000-09-07

2001-12-18

Nguyen, Khiem (Department: 2839)

Electrical connectors

With insulation other than conductor sheath

Plural-contact coupling part

C439S941000

Reexamination Certificate

active

06331126

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to high speed modular jacks of the type mounted on circuit components for mating with plugs on the ends of multi-conductor cables used for transmitting signals between computers.
DESCRIPTION OF THE PRIOR ART
Modular jacks for forming electrical connections between circuit members and plugs mounted on the ends of multi-conductor data-transmission cables are well known. The cables conventionally have eight conductors arranged in four twisted conductor pairs. The jacks and plugs each have eight contacts to form connections between the eight conductors in the cable and the circuit member.
The jacks include a molded plastic body defining a plug recess for receiving a plug mounted on the end of a data transmission cable. Cantilever ends of wire contacts mounted in the body extend into and across the recess to form electrical connections with the contacts on a complimentary plug. The wire contacts run from the recess to pins which extend downwardly from the bottom of the jack. The pins are positioned in preformed holes in the circuit board and are soldered to conductive traces on the circuit board.
The cantilever ends of the wire contacts are spaced across the recess in the block and extend from the recess to the pins in side-by-side parallel relationship, without crossing each other. The pins are spaced across the jack in the same sequence as the contacts are spaced across the recess. The pins are arranged in two rows of pins extending across the body with alternate pins in different rows.
The industry standard for modular jacks requires that the wire pairs in twisted wire data transmission cables be connected to particular cantilever ends in the plug recess. These ends are spaced across the recess in numerical positions
1
through
8
with the cantilever end
1
adjacent one end of the recess and cantilever end
8
adjacent the opposite end of the recess. The industry standard requires that twisted wires in a first pair of twisted wires must be connected to cantilever ends
1
and
2
. A second pair of twisted wires must be connected to cantilever ends
3
and
6
. A third pair of twisted wires must be connected to cantilever ends
4
and
5
and a fourth pair of twisted wires must be connected to cantilever ends
7
and
8
. Modern high speed computing requires rapid transmission of signals along cables, through the plugs and jacks and to computer circuitry with low cross talk between adjacent circuit paths. EIA/TIA Category
5
standards govern permissible near end cross talk generated by modular jacks used for transmitting signals from 1 to 100 MHz. More stringent Category
6
standards govern near end cross talk in modular jack transmitting signals up to 250 MHz. Conventional modular jacks have difficulty meeting Category
5
cross talk standards and cannot meet Category
6
cross talk standards.
Cross talk in conventional signal transmission jacks is believed generated by intermediate portions of the wire contacts which extend along the rear wall of the jack from the cantilever contacts to solder pins at the bottom of the jack. In this type of jack, it is particularly difficult to reduce cross talk between separated contacts
3
and
6
and adjacent contacts which are connected to other signal pairs.
Jacks which generate cross talk at high frequency transmission rates may use specialized compensation systems to compensate for inherent cross talk. It is also possible to incorporate special circuitry in the circuit board supporting the jack to compensate for cross talk generated by the jack. Cross talk compensation systems are expensive, complicate manufacture and are not always effective over a desired range of transmission frequencies.
Thus, there is a need for an improved jack for transmitting high speed signals with very low near end cross talk. The jack should space the wire conductors extending from the plug recess to the pins to reduce cross talk and should eliminate the need for a specialized cross talk compensation system in the jack. The jack should meet Category
5
near end cross talk standards and should, when mounted on a circuit board with the circuit board traces including a cross talk compensation system, meet Category
6
cross talk standards.
SUMMARY OF THE INVENTION
The invention is an improved modular jack for high speed data transmission, typically for establishing electrical connections with an end plug on a data cable having four twisted pairs of conductors. The jack generates very little near end cross talk and meets Category
5
near end cross talk standards. The jack may be mounted on a circuit board having conductive traces arranged to compensate for the low level of cross talk generated by the jack. The jack and board are believed to meet Category
6
near end cross talk standards. The jack is preferably mated with a plug generating low cross talk to form a connection system with low cross talk joining an eight conductor cable to electronic circuitry, typically computer circuitry.
The jack includes wire contacts with conventional cantilever ends extending into a plug recess in the jack for engaging and forming electrical connections with contacts in an inserted plug. The wire contacts intermediate portions run from the cantilever ends to pins projecting below the bottom of the jack. The pins are arraigned in two rows of pins. An end pin in each row of pins is separated from the remaining three pins in the row with the separated pins positioned on opposite ends of the rows. The intermediate portions of the center two wire contacts in the jack cross over each other at the back of the jack so that the pins for these contacts are arranged out of normal sequence across the jack. The intermediate portions do not parallel each other.
In a conventional modular jack, the cantilever ends of the wire contacts are arranged
1
,
2
,
3
,
4
,
5
,
6
,
7
,
8
across the plug recess and the corresponding pins are arranged in spaced staggered rows across the jack in the same
1
,
2
,
3
,
4
,
5
,
6
,
7
,
8
sequence with the even pins in one row and the odd pins in the other row.
In the modular jack of the present invention, crossover of the intermediate portions of the center two wire contacts reverses the positions of the center two pins so that the pins are arranged across the jack in spaced, staggered rows in
1
,
2
,
3
,
5
,
4
,
6
,
7
,
8
sequence.
The positions of the jack pins and the arrangement of the intermediate portions of the wire contacts reduce cross talk generated by the jack and permit the jack to meet Category
5
standards.
In one test, a conventional jack of the type described with pins in the same sequence as the cantilever ends and parallel intermediate portions generated −38 dB of cross talk. In the same test using the jack of the present invention, the cross talk was reduced to −44 dB.
Other objects and features of the invention will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawings illustrating the invention, of which there are four sheets and one embodiment.


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