Fixed impedance shielded differential pair with pairs of side ground plane vias

• US 7,068,119 B2
• Filed: 11/10/2003
• Issued: 06/27/2006
• Est. Priority Date: 09/29/2000
• Status: Expired due to Fees

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Wachel, Robert D.
• Primary Examiner(s): LEE, BENNY T
• Application Number:
  US10/705,777
• Publication Number:
  US 20040148448A1
• Time in Patent Office: 960 Days
• Field of Search: 333/1, 333/4, 333/5, 333/238
• US Class Current: 333/4
• CPC Class Codes: G06F 13/409 Mechanical coupling back panels H05K7/1438

Abstract

A system and method for transferring information at a fast rate between add-in cards in a rack mount system are described. In one embodiment, the invention allow all the add-in cards within the rack mount system to be interconnected. All the main cards within the rack mount system connect to a switch card using point-to-point differential copper pairs. All communication over these differential copper pairs use a messaging protocol that provides a messaging protocol destination address that is used to route the information to the intended destination main card. The messaging protocol may be the Ethernet protocol. In an alternative embodiment, data redundancy is provided by having two switch cards in the rack mount system. A particular main card transmits one set of information to the first switch card and a second set of information (that is identical to the first set of information) to the second switch card. The first switch card routes the first set of information to a particular one of the main card that is the intended destination and the second switch card routes the second set of information to the destination main card (i.e., the first switch card and the second switch card transfer the first set of information and the second set of information to the same destination main card). The destination main card uses the information that is first-to-arrive but if the information that is first-to-arrive has an error, then the later-to-arrive information is selected for use. The point-to-point differential copper pairs between the main cards and the one or more switch cards are referred to as a switched Ethernet interconnect. The switched Ethernet interconnect may be integrated within the mid-plane or using external cables.

Claims

1. A system to obtain a fixed impedance in a differential copper pair, comprising:

a first copper conductor extended along an axis;

a second copper conductor positioned substantially parallel along the axis, wherein the second copper conductor is spaced approximately 5 millimeters from the first copper conductor; and

an insulating casing encompassing the first copper conductor and the second copper conductor, wherein the insulating casing includes two substantially parallel side-ground-planes and two substantially parallel vertical-ground-planes, wherein the two side-ground-planes are each at least 0.015 inches thick and the two vertical-ground-planes are each at least 0.007 inches thick, the side-ground-planes and the vertical-ground-planes respectfully connect to encompass the first and second copper conductors, each of the side-ground-planes includes a pair of vias for connecting the two vertical-ground-planes, wherein the vias in each pair of vias are less than 0.1 inches apart.

2. The insulating casing of claim 1, wherein a first one of the two vertical-ground-planes is located above the first copper conductor and the second copper conductor.

3. The insulating casing of claim 1, wherein a second one of the two vertical-ground-planes attaches perpendicularly to the two side-ground-planes.

4. The insulating casing of claim 1, wherein a second one of the two vertical-ground-planes is located below the first copper conductor and the second copper conductor.

5. The insulating casing of claim 1, wherein at least one of the two side-ground-planes is parallel to at least one of the first copper conductor and the second copper conductor.

6. The insulating casing of claim 1, wherein a first one of the two vertical-ground-planes attaches perpendicularly to the two side-ground-planes.

7. The insulating casing of claim 1, wherein an inner surface of a first one of the two side-ground-planes is located to the left of the first copper conductor and the second copper conductor.

8. The insulating casing of claim 1, wherein an inner surface of a second one of the two side-ground-planes is located to the right of the second copper conductor and the first copper conductor.