An Overview of High-Speed Communications Over Twisted-Pair Cables
by Mark Sauerwald, Applications Engineer, MTS, National Semiconductor Corporation
We have been installing and using twisted-pair cable since the late nineteenth century. Now, in the twenty-first century, it is still the most widely used cable type for high-speed data communications. Twisted-pair cable is commonly used for telephone lines, including the DSL service that brings high-speed internet connectivity into millions of homes. It’s also used for Ethernet connections and the HDMI and DVI connections to your TV receiver and computer monitor, among others. Despite finding twisted-pair cable pretty much everywhere you look, if you search for articles that provide an in-depth analysis of the properties of these cables, you find very little.
There is plenty of material available discussing coax cables, and PCB traces, but despite the broad use of twisted pair, there is not a lot available showing how it behaves under various circumstances. Looking into this, I discovered that one of the reasons for the lack of twisted-pair cable analysis is because you quickly get into some really nasty math…
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