[SI-LIST] Re: Raw cable construction and twisted pairs
- From: steve weir <weirsi@xxxxxxxxxx>
- To: mhaff@xxxxxxx, 'Signal Integrity List' <si-list@xxxxxxxxxxxxx>
- Date: Wed, 23 Nov 2005 12:14:47 -0800
Mike, the number of twists / inch determines the localized imbalance to any
nearby metal for a given frequency. As I recall Dr Johnson likes to write
about that subject.
Steve.
At 11:59 AM 11/23/2005 -0800, Mike Haff wrote:
>Can any of the guru's explain, or know of any good reference materials that
>explain how SI is affected by various numbers of twists per inch for
>differential pairs. In other words, with all other effects being equal,
>what are the different effects of cables with 1-2 twists per inch vs 2-3
>twists per inch (or more, or less)?
>I'm also intrigued by how the newer high speed cables no longer use twisted
>pairs, but parallel pairs. Apparently the noise canceling effects of
>twisting is overshadowed by the need for better skew performance with
>parallel pairs.
>
>Thanks in advance for your comments.
>
>Mike Haff
>Enhance, Inc.
>
>
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