This invention relates generally to electrical connectors, and more particularly, to a modular jack or receptacle with an array layout for reducing crosstalk.
Various electronic systems, such as those used to transmit signals in the telecommunications industry, include connector assemblies with electrical wires arranged in differential pairs. One wire in the differential pair carries a positive signal and the other wire carries a negative signal intended to have the same absolute magnitude, but at an opposite polarity.
An RJ-45 electrical connector, having a plug and outlet jack, is one example of a connector used to transmit electrical signals in differential pairs. An RJ-45 plug has four differential pairs of wires. The plug has a high level of noise due to the arrangement of the wires as determined by industry standards.
Multiple differential pairs are positioned in close proximity to each other in the connector and generate unwanted electromagnetic (EM) signal coupling or crosstalk, which degrades the quality of the signal transmissions. Another problem experienced is mismatched impedance as a signal is transmitted through the plug and the receptacle assembly. The mismatched impedance causes a portion of the electrical signal to be reflected back toward its source. The amount of reflection that occurs due to impedance mismatch may be quantified as return loss.
In addition, connector assemblies are being used to transmit data across higher frequencies and wider bandwidths. As frequencies increase, the system experiences more signal degradation due to EM signal coupling, return loss and impedance mismatch.
Therefore, a need exists for an electrical connector design optimized to negate crosstalk and reduce return loss to improve electrical performance. Certain embodiments of the present invention are intended to meet these needs and other objectives that will become apparent from the description and drawings set forth below.
In one embodiment, a receptacle assembly comprises a housing having front and rear ends. The front end is configured to receive a plug and the rear end is configured to accept wire termination contacts. A circuit board has a plurality of contact holes and is held within the housing. A plurality of array contacts is arranged in a contact array within the housing. Each of the plurality of array contacts comprises a main section and a contact tail. The main section runs generally perpendicular to the circuit board. The contact tail has a first bend to form a first tail sub-section extending parallel to the circuit board and a second bend to form a second tail sub-section extending perpendicular to the circuit board. The second tail sub-section of each of the plurality of array contacts is received by one of the plurality of contact holes in the circuit board.
In another embodiment, a receptacle assembly comprises a housing having front and rear ends. The front end is configured to receive a plug and the rear end is configured to accept wire termination contacts. A circuit board is held within the housing and has first and second sides located opposite one another and top and bottom ends located opposite one another. The circuit board comprises a plurality of contact holes arranged in a contact array pattern and a plurality of wire termination contact holes arranged in a wire termination contact pattern. A plurality of array contacts is arranged in a contact array within the housing. The contact array comprises at least second and third differential pairs. The plurality of wire termination contact holes configured to receive the wire termination contacts associated with the second differential pair are located proximate the top end and the second side of the circuit board and the plurality of wire termination contact holes configured to receive the wire termination contacts associated with the third differential signal pair are located proximate the bottom end and the first side of the circuit board.
The foregoing summary, as well as the following detailed description of certain embodiments of the present invention, will be better understood when read in conjunction with the appended drawings. It should be understood that the present invention is not limited to the arrangements and instrumentality shown in the attached drawings.
In this example, the wire termination contacts 113 are insulation displacement contacts (IDCs), however, other connection means may be used. The wires within the cable terminate at an IDC end of the IDC contacts. The opposite end of the IDC contacts interface with the circuit board 148 within the wire termination contact holes. The wire termination contacts 113 terminate at the circuit board 148 with eye of the needle contacts, compliant pins, solder, press-in connection or other means known to those skilled in the art.
The rear edge 105 includes posts 107 that are configured to be received in holes 109 in the front face 150 of the circuit board 148. The posts 107 may perform alignment and/or locking functions, in order to position and hold the rear edge 105 against the front face 150 of the circuit board 148 in a desired alignment and orientation. The base 122 includes a series of parallel notches 123 formed therein which extend to the lead edge 103 and are spaced apart from one another in a desired manner. The base 122 also includes a bridge 125 located proximate the rear edge 105. The bridge 125 has a series of posts 127 extending upward therefrom and spaced apart from one another by gaps 129 aligned with the notches 123. The array contacts in the contact array 106 have an interference fit with the posts 127 and gaps 129.
The contact array 106 includes array contacts 124, 126, 128, 130, 132, 134, 136 and 138 that are arranged parallel to one another and oriented to extend from within the parallel notches 123 proximate the lead edge 103 to the rear edge 105 of the base 122. Eight contacts are illustrated in the contact array 106; however, more or less than eight contacts may be used. Array contacts 124 and 126 form a first differential pair 140, array contacts 128 and 134 form a second differential pair 142, array contacts 130 and 132 form a third differential pair 144, and array contacts 136 and 138 form a fourth differential pair 146. Array contacts 124 and 126, 130 and 132, and 136 and 138 of the first, third and fourth differential pairs 140, 144 and 146, respectively, are located immediately adjacent one another. The array contacts 128 and 134 of the second differential pair 142, however, are not located immediately adjacent one another. Instead, the array contacts 128 and 134 of the second differential pair 142 are split or separated from one another by intervening third differential pair 144. The array contact 128 is adjacent to the array contacts 126 and 130 of the first and third differential pairs 140 and 144, respectively, while the array-contact 134 is adjacent to the array contacts 132 and 136 of each of the third and fourth differential pairs 144 and 146. The array contacts 124, 126, 128, 130, 132, 134, 136 and 138 extend along the base 122 in a co-planar arrangement and have contact tails 216 (
It should be understood that the circuit board 148, base 122, and the receptacle assembly 100 may vary in size, depending on customer specifications. For example, it may be desirable to make the receptacle assembly 100 as small or compact as possible. Also, further enhancements may be added to the circuit board 148 to modify the transmitted signals.
The contact array 106 enters the circuit board 148 in the contact entry pattern 153 to optimize signal integrity, such as by minimizing noise due to crosstalk, while providing for the configuration of the contact array 106. As illustrated in
Traces (not shown) electrically connect each of the contact holes 188, 190, 192, 194, 196, 198, 200 and 202 within the central portion 164 with a corresponding one of the wire termination contact holes 170, 172, 174, 176, 178, 180, 182, and 184 in either the top or bottom portion 166 or 168. Each of the holes has been provided with a number (corresponding to a contact or pin) within
Each of the array contacts 124, 126, 128, 130, 132, 134, 136 and 138 has a contact tail 216. Each contact tail 216 is bent to form a first bend 224 of approximately 90 degrees, wherein the array contacts 124, 128, 132 and 136 are bent in an upward direction as indicated by arrow A and the array contacts 126, 130, 134 and 138 are bent in a downward direction as indicated by arrow B. A first tail sub-section 228 extends upwards or downwards, parallel to the circuit board 148 for one of two distances, and then a second bend 226 of approximately 90 degrees is formed. A second tail sub-section 222 extends perpendicular to the circuit board 148 and through one of the contact holes 188, 190, 192, 194, 196, 198, 200 and 202 in the circuit board 148, forming the contact entry pattern 153 (
The spatial relationship of the contact holes 188, 190, 192, 194, 196, 198, 200 and 202 with respect to one another and the spatial relationship of the wire termination contact holes 170, 172, 174, 176, 178, 180, 182, and 184 with respect to one another is determined to achieve a desired electrical performance. For example, the contact holes 188, 190, 192, 194, 196, 198, 200 and 202 and wire termination contact holes 170, 172, 174, 176, 178, 180, 182, and 184 may form patterns for coupling and isolating certain contacts.
The wire termination contact pattern 154 will be discussed first, while the contact entry pattern 153 will be discussed further below. In the cable connected to the wire termination contacts 113 of the wire connector housing 112, the two wires of each wire pair are twisted together. In an RJ-45 application, the wires are paired as wire pairs 1/2, 3/6, 4/5 and 7/8, which are associated with the first, second, third and fourth differential pairs 140, 142, 144 and 146, respectively. Each wire pair is received by wire termination contact holes located proximate different corners of the board 148. Specifically, wire pair 1/2 is received by wire termination contact holes 178 and 180 proximate a first corner, wire pair 3/6 is received by wire termination contact holes 170 and 172 proximate a second corner, wire pair 7/8 is received by wire termination contact holes 182 and 184 proximate a third corner, and wire pair 4/5 is received by wire termination contact holes 174 and 176 proximate a fourth corner.
The wire termination contact holes 170, 172, 174, 176, 178, 180, 182, and 184 are arranged, in part, to avoid creating additional noise in the receptacle assembly 100. As industry standards dictate, the plug contains sizable noise with the most noise occurring between the differential pairs 142 and 144. Because this pair combination has the most noise, the wire termination contact pattern 154 isolates the wire pairs 3/6 and 4/5 from one another. Referring to
The wire termination contact pattern 154 also takes into consideration the ease of connecting the cable to the receptacle assembly 100. Two color schemes determined by industry standards for the RJ-45 are called 568A and 568B and match pin numbers to wire colors of a cable. Two sets of wire pairs are typically designated specific colors, and therefore, within the cable, wire pair 4/5 is blue, and wire pair 7/8 is brown. For pattern 568A, wire pair 1/2 is green, and wire pair 3/6 is orange. Alternatively, for pattern 568B, wire pair 1/2 is orange and wire pair 3/6 is green. Another consideration relates to the orientation of the wires within the cable jacket. Although not required by the industry, a common wire color breakout is blue-orange-green-brown that rotates either in the clockwise (CW) or counter-clockwise (CCW) direction depending upon which end of the cable is being viewed. Therefore, there are four main patterns that may be presented: A-pattern and CCW, A-pattern and CW, B-pattern and CCW and B-pattern and CW. The wire termination contact pattern 154 was chosen so that one of these four main patterns matches directly to the jack without the need for altering or crossing over the wire pairs within the natural orientation of the cable resulting in ease of installation where possible. The pattern chosen for this embodiment was B-pattern and CCW.
While corresponding to the industry, the wire termination contact pattern 154 further improves performance by separating noisy pairs. The wire pair 4/5 is blue and corresponds to the wire termination contact holes 174 and 176, and the wire pair 3/6 corresponds to the wire termination contact holes 170 and 172, which are located in an opposite corner of the board 148 with respect to the wire termination contact holes 174 and 176. The wire pair 3/6 may be either green or orange. Therefore, in one embodiment, the wire pair 1/2 is orange and corresponds to wire termination contact holes 178 and 180, while the wire pair 3/6 is green and corresponds to wire termination contact holes 170 and 172. In another embodiment, the wire pair 1/2 may be green while the wire pair 3/6 may be orange.
The contact entry pattern 153 will now be discussed. As stated previously, in an RJ-45 plug, one of the four differential pairs is split around another. Industry standards require a split pair and also dictate how much noise needs to occur in the plug. The highest degree of crosstalk is created between these two pairs, but the other pair combinations also exhibit crosstalk that is not insignificant. This is partly due to the large parallel blades in the plug, and sometimes, the parallel nature of the wires as they are dressed into the plug. Therefore, it is desirable to counteract this noise in the receptacle assembly 100, such as through compensation in the receptacle assembly 100, so the mated connector (the plug and the receptacle assembly 100 joined together) has a significantly smaller amount of noise than the plug alone.
A first group 230 includes the contact holes 188, 192 and 196 arranged in a triangular layout. A circle 232, which may have a minimum diameter of 0.04 inch, captures the center 262 of each of the contact holes 188, 192 and 196. In one embodiment, the circle 232 may have a diameter of 0.082 inch. Optionally, the circle 232 may have a diameter of up to 0.140 inch. A second group 234 includes the contact holes 194, 198 and 202 which are also arranged in a triangular layout. A circle 236 captures the center 262 of each of the contact holes 194, 198 and 202 and may also have a diameter from 0.04 inch to 0.140 inch.
The contact entry pattern 153 may be further described by referring again to
As discussed previously, the eight parallel blades in the plug experience crosstalk. Regarding second differential pair (blades 3/6) and third differential pair (blades 4/5), blades 3 and 4 and blades 5 and 6 have the greatest level of noise due to their close proximity with each other. Correspondingly, in the receptacle assembly 100, the array contacts' 128 and 130 and the array contacts 132 and 134 experience a higher level of noise due to their close proximity to one another. It is desired to isolate the sets of contacts experiencing the higher level of noise. Thus, the array contacts 128 and 130 are received by the contact holes 192 and 194, respectively, which are located away from each other, and the array contacts 132 and 134 are received by contact holes 196 and 198, respectively, which are located away from each other. In
The noise in the receptacle assembly 100 may be further counteracted through compensation by placing other array contacts close to one another. The array contacts 128 and 132 are received by contact holes 192 and 196, respectively, which are located in close proximity to each other, and the array contacts 130 and 134 are received by contact holes 194 and 198, respectively, which are located in close proximity to each other. In
Three of the differential pairs experience a secondary level of noise, or second tier of crosstalk, in the plug. The second differential pair (blades 3/6) experiences a high level of noise with both the first differential pair (blades 1/2) and fourth differential pair (blades 7/8) due to their proximity in the plug and because the second differential pair is a split pair.
To isolate signals experiencing a high level of noise, the array contacts 126 and 128 are received by contact holes 190 and 192, respectively, which are located away from each other, and array contacts 134 and 136 are received by contact holes 198 and 200, respectively, which are located away from each other. In
Return loss which occurs throughout the jack and the receptacle assembly 100 is also considered. A signal sent down two pins (or contacts or wires) in a differential pair has an impedance based on at least one of cross-section of the conductor, space between the conductors and the dielectric constant separating the two conductors in a pair. The adjacent array contacts of the first, third and fourth differential pairs 140, 144 and 146 have essentially the same geometry, and are close together in the receptacle assembly 100, resulting in an impedance between the array contacts of each pair that is lower than desired. By increasing the impedance to match the target impedance, such as 100 ohms, the return loss is improved. Therefore, contact holes 200 and 202 receiving array contacts 136 and 138, respectively, of the fourth differential pair, are placed farther apart with respect to each other, as are contact holes 188 and 190 receiving array contacts 124 and 126, respectively, of the first differential pair, and contact holes 194 and 196 receiving array contacts 130 and 132, respectively, of the third differential pair. Distance between the contact holes of a differential pair may be increased to increase the impedance, providing a more favorable return loss.
While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.
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