Differential transmission line pairs using a coupling orthogonalization approach to reduce cross-talk

Patent metadata

Field	Value
Publication number	US-9240619-B2
Application number	US-201113096808-A
Country	US
Kind code	B2
Filing date	Apr 28, 2011
Priority date	Apr 28, 2011
Publication date	Jan 19, 2016
Grant date	Jan 19, 2016

Abstract

An apparatus is provided. The apparatus generally comprises a plurality of pairs of differential transmission lines. The plurality of pairs of differential transmission lines includes a set of pairs of differential transmission lines with each pair of differential transmission lines from the set of pairs of differential transmission lines including at least one twist to alternate current direction. Also, the plurality of differential transmission lines are arranged such that alternating current directions substantially eliminate cross-talk across the plurality of pairs of differential transmission lines.

First claim

The invention claimed is:

1. An apparatus comprising:
a plurality of pairs of differential transmission lines,
wherein the plurality of pairs of differential transmission lines includes a set of pairs of differential transmission lines with at least one pair of differential transmission lines from the set of pairs of differential transmission lines including at least one twist to alternate current direction, and
wherein the plurality of pairs of differential transmission lines are arranged such that alternating current directions substantially eliminate cross-talk across the plurality of pairs of differential transmission lines, wherein the plurality of pairs of differential transmission lines are substantially parallel to one another, and wherein each pair of differential transmission lines is separated from each adjacent pair of differential transmission lines by a first distance, and wherein differential transmission lines in each pair of differential transmission lines are separated from one another by a second distance, and wherein the first distance is greater than the second distance,
wherein each pair of differential transmission lines includes a positive line and a negative line, and wherein the cross-coupling between an i th and a j th differential pair is a linear combination of cross-couplings of the positive and negative lines of each of the i th and j th differential pair with one another, wherein the cross-couplings of the positive and negative lines of each of the i th and j th differential pair with one another are each a function of a total distance between the i th and j th differential pair and currents traversing the i th and j th differential pair,
and wherein the at least one twist substantially orthogonalizes cross-couplings between each pair of differential transmission lines.

2. The apparatus of claim 1 , wherein the linear combination of cross-couplings of the positive and negative lines of each of the i th and j th differential pair with one another is:
φ i,j =φ ia,ja −φ ia,jb −φ ib,ja +φ ib,jb ,

φ ia,ja is the cross-coupling between the positive lines of the ith and jth differential pair, φ ia,jb is the cross-coupling between the positive line of the ith differential pair and the negative line of the jth differential pair, φ ib,ja is the cross-coupling between the negative line of the ith differential pair and the positive line of the jth differential pair, φ ib,jb is the cross-coupling between the negative lines of the ith and jth differential pair, and wherein φ ia,ja , φ ia,jb , φ ib,ja , and φ ib,jb are:

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Assignees

• Howard Gregory E
• Akour Amneh
• Fan Yanli
• Muth Karlheinz
• Morgan Mark W
• Texas Instruments Inc

Inventors

• Howard Gregory E
• Akour Amneh
• Fan Yanli
• Muth Karlheinz
• Morgan Mark W

Classifications

• H10W44/223

  Differential pair signal lines · CPC title

• H10W44/20

  at high-frequency [HF] or radio frequency [RF] · CPC title

• H05K2201/09245

  Crossing layout · CPC title

• H05K1/0245

  Lay-out of balanced signal pairs, e.g. differential lines or twisted lines · CPC title

• H01P3/026

  Coplanar striplines [CPS] · CPC title