Through-Hole and Multi-Planar Technology
Connector Hardware Performance Enhancement Techniques:
Siemon's Patented Through-Hole and Multi-Planar Reactive Balance Technology
Before the advent of category rated cabling, many designers were ready to invest in proprietary technologies for the implementation of advanced signaling applications. Nowadays, everyone knows that twisted-pair components are more than ready to face gigabit transmission head-on! The high frequency capabilities of connecting hardware are a direct result of engineering research that has culminated in a thorough understanding of component performance and the development of innovative methods to overcome the electrical shortcomings of the mated jack/plug connection.
Regardless of the type or capabilities of the transmission media used for an installation, the integrity of a cabling infrastructure is only as good as the individual components that bind it together. Historically, the near-end crosstalk (NEXT) performance of the modular jack/plug connection has always been the "weak link" in cabling. As shown in figure 1, the NEXT performance of a modular connection is limited by the presence of a "split" pair in the T568A or T568B wiring scheme. Because balanced twisted-pair transmission relies on symmetry between the two conductors in each pair, any disturbance to the natural cable lay can adversely affect performance. In particular, separating the cable conductors to terminate the split pair on pins 3 and 6 changes the electrical balance in such as way as to degrade crosstalk performance. The close proximity of multiple pairs in the plug contributes to additional crosstalk among all pair combinations. The modular jack also adds crosstalk between pairs. To improve the performance of the modular connection, Siemon engineers have undertaken the task of characterizing the electrical unbalance resulting from the mated plug/jack connection and incorporating corrective compensation techniques into their product designs.
The cable untwisting, positioning, and flattening techniques that are employed to terminate a modular plug result in an electrical unbalance that is related to changes in the capacitive (the ability to store a voltage) and inductive (the ability to store a current) properties of each pair. The changes are further compounded by the unbalances within the modular jack and any small mismatch that may be due to the connecting hardware circuit path. By identifying the areas where these losses occur and determining the magnitude of mismatch, small reactive elements (having both capacitive and inductive properties) can be designed back into the connecting hardware to correct inherent unbalances and restore NEXT performance to desired levels. Keep in mind that implementation of these techniques are only effective for products that are designed with minimal mismatch to begin with. As with medication, bigger doses of compensation do not necessarily provide better results.
Because the electrical tuning needed to correct the electrical unbalance requires small, precise changes in voltage magnitude and phase, engineers have been creative in developing innovative technologies for reactive compensation. By necessity, the designs must be economical and exhibit high performance repeatability in a manufacturing environment. Compensation may be added to the connecting hardware printed circuit path or may be integral to the construction of the connector. The Siemon Company holds numerous patents for various methods of achieving electrical balance in connecting hardware.
The Siemon CT® series category 5 couplers, shown in figure 2, utilize patented "though-hole" reactive balancing technology to achieve consistent transmission performance. It is an excellent example of a printed circuit board design containing reactive balancing elements within the circuit path. As shown in figure 3, the CT® coupler employs the use of plated through holes that are arranged and interconnected in a grid pattern on the printed circuit board. The holes are sized, spaced, and interconnected in a specific configuration to provide well-tuned reactive compensation. Location of the holes between selected leads of the modular jacks and the IDC contacts ensures precision placement of the reactive elements.
Figure 2: The Siemon CT® series category 5
couplers utilize patented through-hole reactive
Figure 3: Close-up view of reactive through-hole balancing circuitry
Because the reactive elements may be added in a parallel or series configuration, the designer has infinite control over the outlet's inductive and capacitive reactance. This design approach offers flexibility and allows for minute changes in reactive balancing to achieve optimum performance. This design may be observed in several of Siemon's other product lines including the HD5® series patch panels and the SM® surface mount connectors.
The Siemon Company's innovative circuit board designs go beyond transmission performance. Siemon uses their S110-D connecting blocks that include Siemon's own patented compliant pin (solderless) technology to achieve the most reliable circuit board connection in the industry. This military approved press-fit design allows the use of a multi-pair impact tool thus saving significant installation time while ensuring the integrity of the connection. Traditional solder tail designs may fail due to cracked solder joints when subjected to the force exerted by an impact tool.
An example of a compensation design built integral to the connector is Siemon's multi-planar technology utilized in the Siemon MAX module. The exploded view in figure 4 shows that the MAX module is actually a laminate assembled from three layers of stamped contacts separated by dielectric barriers. The reactive plates provide inductive and capacitive coupling that reduces crosstalk while maintaining pair balance. The series configuration ensures that current passes through the plates (as opposed to a shunt configuration that is known to contribute to resonance in a short link configuration). The use of multi-planar parallel plate contacts offers a significant advantage over other lead-frame compensation styles because the design allows for multi-dimensional optimization between contact pairs to ensure superior performance. The flexibility offered by this design approach is that any two conductors may be selectively positioned adjacent to one another for optimal performance. This type of construction also allows for independent tuning of both input and output connections (the plug and IDC ends of the outlet) to assure consistent performance regardless of its orientation relative to active equipment.
As telecommunications standards are refined to meet the evolving demands of ever-increasing information throughput to the desktop, it is critical that today's cabling products make use of innovations to provide the highest possible reliability and transmission performance. The through-hole technology employed by the Siemon CT®, HD5®, and SM® series outlets and patch panels, and the multi-planar contact construction exemplified in the Siemon MAX module are innovations that provide multi-dimensional design latitude to consistently achieve optimum transmission performance, both as components and as part of a telecommunications channel. These technologies enable The Siemon Company to offer products today that will support enhanced performance requirements and emerging gigabit applications of tomorrow.
Rev. C, 7/99