Patent Grant
7166000
The present invention relates generally to communication connectors and more particularly to near-end crosstalk (NEXT) and far-end crosstalk (FEXT) compensation in communication connectors.
In an electrical communication system, it is sometimes advantageous to transmit information signals (video, audio, data) over a pair of wires (hereinafter “wire-pair” or “differential pair”) rather than a single wire, wherein the transmitted signal comprises the voltage difference between the wires without regard to the absolute voltages present. Each wire in a wire-pair is susceptible to picking up electrical noise from sources such as lightning, automobile spark plugs, and radio stations, to name but a few. Because this type of noise is common to both wires within a pair, the differential signal is typically not disturbed. This is a fundamental reason for having closely spaced differential pairs.
Of greater concern, however, is the electrical noise that is picked up from nearby wires or pairs of wires that may extend in the same general direction for some distances and not cancel differentially on the victim pair. This is referred to as crosstalk. Particularly, in a communication system involving networked computers, channels are formed by cascading plugs, jacks and cable segments. In such channels, a modular plug often mates with a modular jack, and the proximities and routings of the electrical wires (conductors) and contacting structures within the jack and/or plug also can produce capacitive as well as inductive couplings that generate near-end crosstalk (NEXT) (i.e., the crosstalk measured at an input location corresponding to a source at the same location) as well as far-end crosstalk (FEXT) (i.e., the crosstalk measured at the output location corresponding to a source at the input location). Such crosstalks occur from closely-positioned wires over a short distance.
In all of the above situations, undesirable signals are present on the electrical conductors that can interfere with the information signal. When the same noise signal is added to each wire in the wire-pair, the voltage difference between the wires will remain about the same and “differential” cross-talk is not induced, while at the same time the average voltage on the two wires with respect to ground reference is elevated and “common mode” crosstalk is induced. On the other hand, when an opposite but equal noise signal is added to each wire in the wire pair, the voltage difference between the wires will be elevated and differential crosstalk is induced, while the average voltage on the two wires with respect to ground reference is not elevated and common mode crosstalk is not induced.
U.S. Pat. No. 5,997,358 to Adriaenssens et al. (hereinafter “the '358 patent”) describes a two-stage scheme for compensating differential to differential NEXT for a plug-jack combination (the entire contents of the '358 patent are hereby incorporated herein by reference, as are U.S. Pat. Nos. 5,915,989; 6,042,427; 6,050,843; and 6,270,381). Connectors described in the '358 patent can reduce the internal NEXT (original crosstalk) between the electrical wire pairs of a modular plug by adding a fabricated or artificial crosstalk, usually in the jack, at one or more stages, thereby canceling or reducing the overall crosstalk for the plug-jack combination. The fabricated crosstalk is referred to herein as a compensation crosstalk. This idea can often be implemented by twice crossing the path of one of the differential pairs within the connector relative to the path of another differential pair within the connector, thereby providing two stages of NEXT compensation. Another common technique is to cross the conductors of pairs 1, 2 and 4 (as defined by 47 C.F.R. 68.502), leaving the conductors of pair 3 uncrossed (see, e.g., U.S. Pat. No. 6,464,541 to Hashim et al.), then to include a second compensation stage (e.g., in the form of capacitive compensation using one or more capacitors) on an attached printed wiring board. This scheme can be more efficient at reducing the NEXT than a scheme in which the compensation is added at a single stage, especially when the second and subsequent stages of compensation include a time delay that is selected to account for differences in phase between the offending and compensating crosstalk. This type of arrangement can include capacitive and/or inductive elements that introduce multi-stage crosstalk compensation, and is typically employed in jack lead frames and PWB structures within jacks. These configurations can allow connectors to meet “Category 6” performance standards set forth in ANSI/EIA/TIA 568, which are primary component standards for mated plugs and jacks for transmission frequencies up to 250 MHz.
Alien NEXT is the differential crosstalk that occurs between communication channels. Obviously, physical separation between jacks will help and/or typical crosstalk approaches may be employed. However, a problem case may be “pair 3” of one channel crosstalking to “pair 3” of another channel, even if the pair 3 plug and jack wires in each channel are remote from each other and the only coupling occurs between the routed cabling. This form of alien NEXT occurs because of pair to pair unbalances that exist in the plug-jack combination, which results in mode conversions from differential NEXT to common mode NEXT and vice versa. To reduce this form of alien NEXT, shielded systems containing shielded twisted pairs or foiled twisted pair configurations may be used. However, the inclusion of shields can increase cost of the system. Another approach to reduce or minimize alien NEXT utilizes spatial separation of cables within a channel and/or spatial separation between the jacks in a channel. However, this is typically impractical because bundling of cables and patch cords is common practice due to “real estate” constraints and ease of wire management.
In spite of recent strides made in improving mated connector (i.e., plug-jack) performance, and in particular reducing crosstalk at elevated frequencies (e.g., 500 MHz—see U.S. patent application Ser. No. 10/845,104, entitled NEXT High Frequency Improvement by Using Frequency Dependent Effective Capacitance, filed May 4, 2004, the disclosure of which is hereby incorporated herein by reference), channels utilizing connectors that rely on either these teachings or those of the '358 patent can still exhibit unacceptably high alien NEXT at very high frequencies (e.g., 500 MHz). As such, it would be desirable to provide connectors and channels used thereby with reduced alien NEXT at very high frequencies.
One specific type of communications jack is illustrated in U.S. Pat. No. 6,443,777 to McCurdy, the disclosure of which is hereby incorporated herein in its entirety, and is shown in
The cross-section of the contact wires 12 at the contact point is shown in
In Table 1, as well in subsequent tables to be presented, all tabulated inductive responses (XL) were derived using calculations that assumed magnetic coupling between line filaments, and tabulated capacitive responses (XC) used calculations based on capacitive coupling between circular wires having circumference equivalent to actual 10×17 mil cross-sections. (Equation references are in Walker, Capacitance, Inductance, and Crosstalk Analysis, Sections 2.2.8 and 2.3.8). The latter calculations are also approximate because shielding effects are not taken into consideration, but the results are sufficient for demonstrating significant contrasts. Further, differential to common mode reponses (DIFF TO COM NEXT) assume a common mode impedance of 75 ohms, a value whose absolute value need not be exact for this purpose. Due to the symmetry of the contact wire arrangement, differential to differential NEXT responses (DIFF to DIFF NEXT) of pair 1 to side pair 4 or pair 3 to side pair 4 is identical in magnitude and polarity to pair 1 to side pair 2 and pair 3 to side pair 2, respectively. However DIFF to COM NEXT responses for pair 1 to 4 (or 4 to 1) and pair 3 to pair 4 (or 4 to 3) have the same magnitude, but of opposite polarity of pair 1 to 2 (or 2 to 1) and pair 3 to pair 2 (or 2 to 3), respectively.
The polarity of the crosstalk generated by the inline structure of
In some prior jacks, the individual contact wires of the jack are made to separate from each other on the lead frame as they approach the PWB into which they mount and terminate. The resulting stagger pattern is seen in U.S. Pat. No. 6,086,428 to Pharney et al. The cross-section of this region of contact wires of such a jack is shown in
Notably, the per unit length coupling polarity has flipped relative to the in-line configuration for the differential to differential NEXT of the 1–3 and 2–3 pair combinations, so these pair combinations now yield compensating coupling. (Again, differential to differential NEXT for the 3–4 pair combination is the same as the 2–3 pair combination). Dimensionally, the longer the lead frame is after the polarity has flipped and before attachment to the PWB, the more cross talk compensation is introduced. It has been the 1–3 and 2–3 differential to differential compensation aspects that have rendered the stagger pattern advantageous (even though the 1–2 differential to differential NEXT is counterproductive, the levels are such that normal compensating procedures on the PWB have been sufficient). But with higher performance standards, balance is now a significant variable, and the large counterproductive differential to common mode pair 3 to pair 2 (and pair 3 to pair 4) mode conversion of the stagger pattern is highly undesirable.
The prior jack lead frame embodiment shown in
Although differential to differential compensation levels are about the same as the staggered pattern of
U.S. Pat. No. 6,443,777 to McCurdy, supra, discloses a prior art jack in which the fixed end segments of pair 3 include traverses that cause portions of the fixed end segments of the contact wires of pairs 1 and 3 to form a rectangle (see
As a first aspect, the present invention is directed to a communications jack, comprising: a dielectric mounting substrate; and a plurality of contact wires, each of the contact wires having a contact segment, a compensating segment in electrical connection with the contact segment, and a base in electrical connection with the compensating segment and mounted in the mounting substrate. The contact segments are generally transversely aligned and parallel with each other. The contact segments are arranged in pairs, with a first pair of contact segments being immediately adjacent each other, a second pair of contact segments being immediately adjacent each other and positioned one side of the first pair, a fourth pair of contact segments being immediately adjacent each other and positioned on an opposite side of the first pair, and a third pair of contact segments sandwiching the first pair, with one of the contact segments of the third pair being disposed between the first and second pairs, and the other of the contact segments being disposed between the first and fourth pairs. Sections of the compensation segments of the second pair are substantially vertically aligned with each other, and sections of the compensation segments of the fourth pair are substantially vertically aligned with each other. This configuration can improve differential to common mode crosstalk compensation, particularly between the contact wires of the third pair and the second and fourth pairs of contact wires.
As a second aspect, the present invention is directed to a communications jack, comprising: a dielectric mounting substrate; and a plurality of contact wires, each of the contact wires having a contact segment, a compensating segment in electrical connection with the contact segment, and a base in electrical connection with the compensating segment and mounted in the mounting substrate. The contact segments are generally transversely aligned and parallel with each other. The contact segments are arranged in pairs, with a first pair of contact segments being immediately adjacent each other, a second pair of contact segments being immediately adjacent each other and positioned one side of the first pair, a fourth pair of contact segments being immediately adjacent each other and positioned on an opposite side of the first pair, and a third pair of contact segments sandwiching the first pair, with one of the contact segments of the third pair being disposed between the first and second pairs, and the other of the contact segments being disposed between the first and fourth pairs. At least one of sections of the compensation segments of the first pair and sections of the compensation segments of the third pair are substantially vertically aligned. In some embodiments, both the sections of the compensation segments of the first pair and the sections of the compensation segments of the third pair are substantially vertically aligned. Again, in this configuration, improved differential to common mode crosstalk compensation, particularly between the contact wires of the third pair and the second and fourth pairs of contact wires, can result.
As a third aspect, the present invention is directed to a communications jack, comprising: a dielectric mounting substrate; and a plurality of contact wires, each of the contact wires having a contact segment, a compensating segment in electrical connection with the contact segment, and a base in electrical connection with the compensating segment and mounted in the mounting substrate. The contact segments are generally transversely aligned and parallel with each other. The contact segments are arranged in pairs, with a first pair of contact segments being immediately adjacent each other, a second pair of contact segments being immediately adjacent each other and positioned one side of the first pair, a fourth pair of contact segments being immediately adjacent each other and positioned on an opposite side of the first pair, and a third pair of contact segments sandwiching the first pair, with one of the contact segments of the third pair being disposed between the first and second pairs, and the other of the contact segments being disposed between the first and fourth pairs. The compensating segments are configured and arranged such that differential to common mode crosstalk generated between the contact segments of the second and third pairs is opposite in polarity to the differential to common mode crosstalk generated between the compensating segments of the second and third pairs. Once again, this configuration can improve differential to common mode crosstalk compensation, particularly between the contact wires of the third pair and the second and fourth pairs of contact wires.
The present invention will be described more particularly hereinafter with reference to the accompanying drawings. The invention is not intended to be limited to the illustrated embodiments; rather, these embodiments are intended to fully and completely disclose the invention to those skilled in this art. In the drawings, like numbers refer to like elements throughout. Thicknesses and dimensions of some components may be exaggerated for clarity.
In addition, spatially relative terms, such as “under”, “below”, “lower”, “over”, “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “under” or “beneath” other elements or features would then be oriented “over” the other elements or features. Thus, the exemplary term “under” can encompass both an orientation of over and under. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
Well-known functions or constructions may not be described in detail for brevity and/or clarity.
As used herein the expression “and/or” includes any and all combinations of one or more of the associated listed items.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
This invention is directed to communications connectors, with a primary example of such being a communications jack. As used herein, the terms “forward”, “forwardly”, and “front” and derivatives thereof refer to the direction defined by a vector extending from the center of the jack toward the plug opening of the jack. Conversely, the terms “rearward”, “rearwardly”, and derivatives thereof refer to the direction directly opposite the forward direction; the rearward direction is defined by a vector that extends away from the plug opening toward the remainder of the jack. Together, the forward and rearward directions define the “longitudinal” dimension of the jack. The terms “lateral,” “outward”, and derivatives thereof refer to the direction generally parallel with the plane defined by a wiring board on which jack contact wires are mounted and extending away from a plane bisecting the jack in the center. The terms “medial,” “inward,” “inboard,” and derivatives thereof refer to the direction that is the converse of the lateral direction, i.e., the direction parallel with the plane defined by the wiring board and extending from the periphery of the jack toward the aforementioned bisecting plane. Together, the lateral and inward directions define the “transverse” dimension of the jack. A line normal to the longitudinal and transverse dimensions defines the “vertical” dimension of the jack.
Where used, the terms “attached”, “connected”, “interconnected”, “contacting”, “mounted” and the like can mean either direct or indirect attachment or contact between elements, unless stated otherwise. Where used, the terms “coupled,” “induced” and the like can mean non-conductive interaction, either direct or indirect, between elements or between different sections of the same element, unless stated otherwise.
Turning now to the figures,
Referring to
When a mating plug is received in the plug opening 118, free end segments 119a–119h (also termed “contact segments”) of the contact wires 112a–112h establish electrical contact with corresponding terminals of the mating plug along a plug/jack contact line or interface 120 on the free end portions.
The contact segments 119a–119h of the contact wires 112a–112h are substantially transversely aligned and parallel with one another, as seen in
Typically, as described above, the greatest amount of offending differential to differential crosstalk is developed in plug connectors among the pair 1 and the pair 3 signal paths. It is therefore desirable to obtain equal and opposite levels of both inductive and capacitive crosstalk compensation among the pair 1 and the pair 3 contact wires 112a–112h, in the region between the plug/jack interface 120 and the bases 126 of the contact wires 112a–112h at the rear wall 124 of the jack housing 114. Capacitive coupling may be introduced, for example, via a printed wiring board 144 connected to the bases 126 of the contact wires 112a–112h at the rear of the jack housing 114. See, e.g., U.S. Pat. No. 6,350,158 to Arnett et al., the disclosure of which is hereby incorporated herein by reference in its entirety. In addition, capacitive and inductive coupling may be introduced by the relative configurations of the contact wires 112a–112h themselves, as discussed above.
Turning now to
Between the plug-jack interface 120 and its base 126, each of the four compensating segments 121a, 121d, 121e, 121h extend entirely within a plane that is substantially parallel with a vertical plane V1 that extends between the contact segments 119d, 119e of pair 1 (e.g., the compensating segment 121h of the contact wire 112h—see
In the illustrated embodiment, the stagger distance S1 between the sections 122b, 122d, 122f, 122h and the sections 122a, 122c, 122e, 122g is 0.1 inch, although this distance may vary. Also, the transverse distance D1 between the sections 122b and 122d is 0.12 inch, and the transverse distance D2 between the sections 122e and 122c is 0.04 inch, although each of these distances may vary.
In this configuration, the differential to differential and differential to common mode crosstalk values can be calculated (under the method described above) and are set forth in Table 4.
It can be seen that the large pair 3 to 2 differential to common mode crosstalk is reduced significantly below that of the prior art jack of
Turning now to
In the illustrated embodiment, the stagger distance S2 between the sections 222a, 222b is 0.1 inch, the stagger distance S3 between the sections 222e, 222c is 0.04 inch, and the stagger distance S4 between the sections 222d, 222e is 0.1 inch, although these distances may vary. Also, the transverse distance D3 between the sections 222g, 222h and the substantially vertically aligned sections 222c, 222e, 222d, 222f is 0.12 inch, although this distance may vary.
In this configuration, the differential to differential and differential to common mode crosstalk values can be calculated (under the method described above) and are set forth in Table 5.
This configuration has no mode coversions in the region analyzed and therefore does not add to the detrimental mode conversions generated by typical plugs and or the front end geometries of the lead frame. Further, the differential to differential NEXT compensation for the 1 to 3 and 2 to 3 pair combinations are very efficient for compensation. The pair 1 to 2 differential to differential NEXT compensation is still counterproductive, but may be more manageable, as the values produced are comparable to those of the embodiment analyzed in Table 3.
It should be noted that some unbalance may still exist with the contact wire arrangements of
Referring now to
In the illustrated embodiment, the stagger distance S6 between the sections 322g, 322h is 0.09 inch, and the stagger distance S5 between the sections 322e, 322c is 0.04 inch, although these distances may vary. Also, the transverse distance D4 between the sections 322g, 322h and the substantially vertically aligned sections 322c, 322e, 322d, 322f is 0.14 inch, although this distance may vary.
In this configuration, the differential to differential and differential to common mode crosstalk values can be calculated (under the method described above) and are set forth in Table 6.
Note that the pair 1 to 3 differential to differential and differential to common mode remain the same as for the embodiment of
Those skilled in this art will appreciate that the traversing of the compensating sections described above may also be carried out in other ways. For example, if both compensation sections of a pair include traverses to be come substantially vertically aligned, the pair may be configured such that only one of the compensation sections includes a traverse, with the distance of that traverse being equal to the total of the distances of both of the traverses of the pair illustrated herein. Conversely, if a pair includes only a single traverse, that pair may alternatively be configured such that both of the compensation sections include a traverse, with the sum of the traverses of those compensation sections being equal to the distance of the original traverse. Other configurations may also be suitable for use with this invention.
Those skilled in this art will recognize that other jack configurations may also be suitable for use with the present invention. For example, as discussed above, other configurations of jack frames, covers and terminal housings may also be employed with the present invention. As a further example, communications jacks may be employed within a patch panel or series of patch panels.
The foregoing is illustrative of the present invention and is not to be construed as limiting thereof. Although exemplary embodiments of this invention have been described, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the claims. The invention is defined by the following claims, with equivalents of the claims to be included therein.
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