Twisted pair backplane

• US 5,036,160 A
• Filed: 11/07/1989
• Issued: 07/30/1991
• Est. Priority Date: 11/07/1989
• Status: Expired due to Fees

• Current Assignee: Datum Incorporated (Microchip Technology Incorporated)
• Original Assignee: Crosspoint Systems Incorporated
• Inventors: Jackson, Joseph M.
• Primary Examiner(s): NOT, DEFINED
• Application Number:
  US07/432,472
• Time in Patent Office: 630 Days
• Field of Search: 174/32, 174/33, 174/34, 174/251, 174/262, 333/1, 333/12, 333/161, 333/238, 333/246
• US Class Current: 174/33
• CPC Class Codes: H05K 1/0228 Compensation of cross-talk by a mutually correlated lay-out of printed circuit traces, e.g. for compensation of cross-talk in mounted connectors balanced signal pairs H05K1/0245
• CPC Class Codes: H05K 1/0245 Lay-out of balanced signal pairs, e.g. differential lines or twisted lines
• CPC Class Codes: H05K 2201/044 Details of backplane or midplane for mounting orthogonal PCBs
• CPC Class Codes: H05K 2201/097 Alternating conductors, e.g. alternating different shaped pads, twisted pairs; Alternating components
• CPC Class Codes: H05K 7/1459 Circuit configuration, e.g. routing signals
• CPC Class Codes: H05K 9/0039 Galvanic coupling of ground layer on printed circuit board [PCB] to conductive casing printed shielding conductors, ground planes or power planes for reduction of cross-talk or noise in printed circuits H05K1/0218

Abstract

A backplane having a layer of insulation material, a plurality of lead segments arranged in line and spaced from one another on a first surface of the insulation material, a plurality of cooperating lead segments arranged in line and spaced from one another on a second surface of the insulation material, and connectors for interconnecting the ends of alternate segments on the first and second surfaces to form a first continuous line alternating between lead segments on the first and second surfaces. Connectors are also provided for connecting the ends of alternate segments on the first and second surfaces to form a second continuous line separate from the first line, the first and second lines twisting along the axis of signal propagation to produce a twisted pair in the backplane.

Claims

1. A backplane comprising:

a layer of insulation material;

a plurality of lead segments arranged in line and spaced from one another on a first surface of said insulation material;

a plurality of cooperating lead segments arranged in line and spaced from one another on a second surface of said insulation material;

means for interconnecting the ends of a first portion of alternate segments on said first and second surfaces to form a first continuous line alternating between lead segments on said first and second surfaces;

means for connecting the ends of a second portion of alternate segments on said first and second surfaces to form a second continuous line alternating between lead segments on said first and second surfaces separate from said first continuous line;

said first and second continuous lines twisting along the axis of signal propagation to produce a twisted pair within said backplane;

a plurality of conductive shield layers located parallel with and adjacent to said first and second surfaces of the layer of insulation material;

a plurality of connecting rods connecting said plurality of shield layers through said insulation material; and

said shield layers being ground layers, said first and second continuous lines being internal thereto, said shield layers shielding said first and second continuous lines on two opposing sides.

2. The apparatus of claim 1 wherein said plurality of connecting rods are dispersed through said insulation material in proximity to said first and second continuous lines;

said connecting rods having conductive member extending therefrom for providing shielding above and below said first and second continuous lines so that a coaxial environment is created for said first and second continuous lines.

3. The apparatus of claim 1 wherein said first continuous line and said second continuous line are twisted axially with respect to one another to form said twisted pair such that said first and second continuous lines of said twisted pair move from alternate surfaces of said insulation material in a radially circular fashion, said twisted first and second continuous crossing lines over one another at predefined intervals.

4. The apparatus of claim 3 further comprising:

a plurality of twisted pairs of first and second continuous lines located adjacent one another, each adjacent twisted pair having an opposite, but equal unidirectional twist to that of an adjacent pair so that inductive couplings between adjacent twisted pairs substantially cancel one another.

5. A twisted pair backplane having a plurality of conduction layers, etch layers and insulation layers, said insulation layers separating said conduction and said etch layers, comprising:

a plurality of signal leads located on each of said plurality of etch layers for transmitting signals in said backplane;

a plurality of connecting leads placed at specific intervals through at least one of said insulation layers for connecting said signal leads from one of said plurality of etch layers to the signal leads of another of said plurality of etch layers;

said signal leads and said plurality of connecting leads forming a plurality of twisted signal and return line pairs, each of said twisted signal and return line pairs being formed by said connecting leads connecting specific ones of said signal leads through at least one of said insulation layers such that each of said twisted signal and return line pairs is twisted unidirectionally in said backplane;

a plurality of connecting rods dispersed through said etch layers forming a contact between said plurality of conduction layers;

said conduction layers shielding said twisted signal and return line pairs on two opposing sides; and

said connecting rods having conductive member extending therefrom for providing shielding above and below said twisted signal and return line pairs so that a coaxial environment is created for said twisted signal and return line pairs.

6. The apparatus of claim 5 wherein said plurality of twisted signal and return line pairs are located adjacent to one another, and adjacent twisted signal and return line pairs twist in directions opposite to one another to cancel inductive coupling therebetween.