Electrical connectors – With circuit component or comprising connector which fully... – Termination circuit
Reexamination Certificate
2000-09-13
2002-02-12
Luebke, Renee (Department: 2833)
Electrical connectors
With circuit component or comprising connector which fully...
Termination circuit
C439S676000, C439S941000
Reexamination Certificate
active
06346010
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to electrical connectors, and more particularly, to an improved modular connector for use in data communications and/or telephony.
BACKGROUND OF THE INVENTION
Modular connectors, such as the popular RJ 45 connector, are well known in the communications art.
FIGS. 1A and 1B
show a typical male modular connector
12
, known as the “plug”, and typical female modular connector
14
, known as the “jack”. The plug
12
and the jack
14
connectors mate for communicating signals between the external circuit
16
, in this instance a printed circuit board, and the external circuit
18
, in this instance a computer. The pins
20
of the jack
14
electrically connect to the printed circuit board, and the cable
22
electrically connects the plug
12
to the computer.
FIG. 1B
shows a perspective view of the plug connector
12
and a partially cut away view of the jack connector
14
. The plug connector
12
includes a body
24
, and disposed with the body
24
are a plurality of conductors
28
that include blade-type contacts
30
. The jack connector
14
can include the body
32
, which in turn can include a housing
34
and a lead frame
36
. The plurality of conductors
38
is disposed with the body
32
, and each of the conductors of the plurality include a contacting portion for contacting the contacts
30
of the plug connector
12
when the plug connector
12
is mated with the jack connector
14
. The reference numeral
40
indicates generally the row of contact portions of the plurality of connectors
38
. The lead frame
36
of the body
32
can be included with the body
32
to space and support the plurality of conductors
38
such that contact portions thereof properly electrically connect with the contacts
30
of the plurality of conductors
28
of the plug connector
12
, when the connections are mated.
Although the plug
12
and jack
14
above are each shown with eight conductors, one example of a modular connector, which can use only four conductors, is the ubiquitous telephone jack present in almost every home. Typically, however, the plug
12
and jack
14
will each include eight conductors, as shown in
FIG. 1B
, yielding four data conductor pairs.
The general mechanical design of the modular plug and jack connectors shown
FIGS. 1A and 1B
was determined at a time when the connectors were to be used almost exclusively for the transmission of relatively low frequency signals, such as analog telephone signals. At the present time, however, modular connectors are used at higher and higher frequencies, such as in computer networks. Unfortunately, at these higher frequencies, cross talk between data pairs of conductors becomes increasingly problematic. It is considered that certain aspects of the mechanical design of the typical modular connector contribute to causing the undesired cross talk.
For example, the conductors
28
of the plug connector
12
are very close and run parallel to each other, such that data conductors that should ideally be electromagnetically isolated from one another actually do interact. Cross talk can be categorized as capacitive, wherein the electric field of conductor of one data pair induces a voltage in a conductor of a different data pair, and inductive, wherein the magnetic field of a conductor of one data pair induces a current in a conductor of a different data pair.
The cross talk in modular connections is often further categorized as near-end cross talk, or NEXT, and far-end cross talk, or FEXT. NEXT refers to cross talk that appears as an unwanted signal in one data pair at, for example, the end
42
of plug connector
12
, and is responsive to a signal also entering the end
42
of the plug on another data pair. Such cross talk can be launched onto the external circuit to which the plug connector
12
is electrically connected, such as the computer in FIG.
1
A. Similarly, FEXT refers to cross talk that travels through the plug-jack mated pair. For example, for a desired signal entering the end
42
of the plug connector
12
on one data pair, FEXT refers to an undesired signal appearing at the pins
20
and on a different pair of conductors.
Cross talk becomes progressively worse as the frequency of the electrical signals increases. Cross talk standards are promulgated from time to time. Each new standard is typically stricter than the last, such as by increasing the frequency range and/or lowering the amount of allowable cross talk. For example, the Category
5
standard now in use specifies NEXT up to approximately 100 MHz. The Category
5
standard does not address FEXT. The new Category
6
standard specifies cross talk up to a frequency of 250 MHz. Furthermore, the Category
6
standard specifies limits for both NEXT and FEXT.
Because of the large installed base of older modular connectors, and the need for new connector designs to be backwardly compatible with such older connectors installed in the field, the mechanical arrangement of modular connectors is now standard and subject to little change. Accordingly, design choices can be limited, and the focus is on compensating for the cross talk introduced in the connectors. For example, designers have attempted to meet the Category
5
standard by introducing compensating electronic elements into the external circuits to which the plug and jack are connected, or into the jack and/or plug connectors. These elements typically compensate for the cross talk induced in the plug. For example, the conductors of a jack connector can be arranged to introduce inductive cross talk that cancels cross talk introduced in the plug. Also, it is known to provide capacitors on the external circuit
16
, such as the printed circuit board of
FIG. 1B
, to which the output of the jack connector is electrically connected to compensate for cross talk introduced by the plug connector. While such techniques have been useful at lower frequencies, they are not entirely satisfactory, even in the upper frequency range of Category
5
. The Category
6
specification significantly exceeds the 100 MHz limit of Category
5
to 250 MHz.
There is an additional complication. Designers are wary to attack the problem of cross talk in the Category
6
frequency range by attacking the source, that is by reducing the cross talk introduced in the plug connector, even apart from the general consideration that much of the mechanical design is fixed. This is because many Category
5
jacks in use meet the Category
5
specification by compensating for a known amount of cross talk in the plug. Remove that cross talk, and the “solution”, that is, the compensation in the Category
5
jack, or in the external circuitry associated with the jack, simply becomes the “problem”, and introduces cross talk when such a jack is mated with a newer plug that introduces less cross talk or that includes it own compensation.
Reducing the cross talk in modular connectors, particularly at higher frequencies, such as above the 100 MHz upper limit of the Category
5
specification, can be problematic.
Accordingly, it is an object of the present invention to address one or more of the foregoing disadvantages and drawbacks of the prior art.
It is another object of the present invention to provide an improved modular connector, such as a modular connector having improved cross talk performance.
SUMMARY OF THE INVENTION
In one aspect, the invention provides an improved modular connector such as a jack connector, for mating with another modular connector, such as a plug connector, for electrical connection therewith. The modular connector includes a body and a plurality of conductors disposed with the body. Each of the conductors extends from a first portion to a second end and has a contact portion therebetween, and the contact portions can be substantially parallel and arranged in a row for electrical connection with a row of contacts of the other connector when mated with the modular connector of the invention. The first portions are for connection with an external circuit for communication of
Figueroa Felix O.
Luebke Renee
McCormick Paulding & Huber LLP
The Wiremold Company
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