Twisted Pair Cable with Different Twist Lays for PoE Crosstalk
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Solution Overview
Problem
Existing twisted pair communication cables face challenges in satisfying electrical performance requirements for Power over Ethernet (PoE) applications, particularly as power requirements increase, leading to difficulties in managing crosstalk and noise, especially with the need for higher bandwidth.
Innovation Solution
The development of twisted pair communication cables with 22 AWG or greater conductors, capable of transmitting 100 Watts of power with 88% efficiency over 100 meters, featuring different twist lays for each pair to reduce crosstalk and meet Category 6A standards, including propagation delay skew and direct current resistance unbalance, while incorporating separators and shield layers for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conductor size is increased to meet higher power requirements, then power transmission capability is improved, but cable complexity and difficulty in meeting electrical performance requirements worsen
Solution Approach 1:
The patent applies different twist lays to different twisted pairs within the same cable. Specifically, first and second twisted pairs have a first twist lay, while third and fourth twisted pairs have a second twist lay that is different from the first. This local differentiation allows each pair to be optimized for its specific function (power transmission vs. data communication) while maintaining overall cable performance.
Solution Approach 2:
The patent segments the cable into functionally distinct twisted pairs with different characteristics. By dividing the four twisted pairs into two groups with different twist lays, the cable can simultaneously handle high power transmission on one pair while maintaining data communication performance on another pair, thus resolving the complexity issue.
2Power
If conductor size is increased to transmit higher power, then power transmission capability is improved, but crosstalk and noise management becomes more difficult
Solution Approach 1:
Different twist lays are assigned to different twisted pairs to locally optimize performance. The first twist lay is optimized for power transmission pairs while the second twist lay is optimized for data communication pairs, thereby reducing crosstalk and noise between pairs with different functional requirements.
Solution Approach 2:
The patent introduces an overall twist that acts as an intermediary structure binding the different twisted pairs together. This overall twist helps manage the spatial arrangement and electromagnetic field distribution between pairs with different twist lays, reducing harmful interactions while maintaining the benefits of differentiated pair designs.
3Speed
If bandwidth requirements are increased, then data transmission capability is improved, but cable design difficulty increases
Solution Approach 1:
The patent assigns different twist lays to different twisted pairs to locally optimize for high bandwidth performance. The differentiated twist lays allow specific pairs to be optimized for high-frequency data transmission while others handle power, enabling the cable to meet Category 6A bandwidth requirements without excessive design complexity.
Data Source
AI summary
In a method for forming a Category 6A communication cable suitable for Power over Ethernet applications, four pairs of individually insulated conductors may be provided, and each of the conductors may have a diameter of at least approximately 0.0240 inches. A respective twist lay for each of the pairs may be selected to result in the communications cable having a propagation delay skew of less than approximately 45 nanoseconds per one hundred meters and a direct current resistance unbalance between any two of the four pairs of less than approximately one hundred milliohms per one hundred meters. Each of the four pairs may be twisted based at least in part on the selected twist lays, and a jacket may be formed around the four twisted pairs.