Browse Prior Art Database

CYLINDRICAL BACKPLANE INCREASES BUS PERFORMANCE AND ENABLES BETTER PACKAGING

IP.com Disclosure Number: IPCOM000009470D
Original Publication Date: 1999-Sep-01
Included in the Prior Art Database: 2002-Aug-27
Document File: 3 page(s) / 145K

Publishing Venue

Motorola

Related People

Mark Summers: AUTHOR

Abstract

This paper describes a method of making a backplane design which improves bus performance and enables greater packaging flexibility than con- ventional backplanes.

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Technical MOTOROLA @ Developments

CYLINDRICAL BACKPLANE INCREASES BUS PERFORMANCE AND ENABLES BETTER PACKAGING

by Mark Summers

ting maximum clock frequencies. The space between adjacent boards is generous, enabling a larger class (height) of components to be utilized as well as simplifying system cooling. By arranging the backplane connectors in different planes, as shown in Figure 1, all of the problems associated with conventional backplanes can be minimized. This concept can be applied to any type of bus. The PC1 bus has especially stringent bus loading require- ments.

  This implementation shows connectors mounted to form an interconnect structure. Figure 1 illus- trates this interconnect structure. In this implemen- tation, the interconnect structure is considered to be fabricated in a cost effective manner out of flexible circuits with stiffeners (commonly called rigid-flex circuitry) and then rolled into the final shape. The number of connectors in this interconnect imple- mentation is eight so the form is an octagon.

  Figure 2 illustrates how this interconnect struc- ture becomes the core component into a cost effec- tive circular card cage. In this example, eight cards can be plugged into the eight connectors. Note that the arrangement of the cards (like pie slices) allows much taller components than traditional rectangular shaped card cages. Also note that this circular arrangement allows the connectors on the intercon- nect structure to have a much tighter circuit spacing between the connectors. The main bridging circuit- ry is located on a stiffener section which is located at the center of the interconnect structure (refer to Figure 1 again).

   This main bridging circuitry is designed to allow easy expansion bridging to other circular card cages through built-in bridging connectors located above and below interconnect structures. Hence building an entire system by adding circular card- cages into a tower form. Figure 2 illustrates this concept. In addition, cooling for such a system is

0 Momls. Inc. 1999 112 September 1999

ABSTRACT

  This paper describes a method of making a backplane design which improves bus performance and enables greater packaging flexibility than con- ventional backplanes.

PROBLEMS WITH CONVENTIONAL BACKPLANES

  Conventional backplane busses are fabricated with an ordinary printed wiring board with all of the connectors existing in one plane. Backplane busses are sensitive to bus length and loading. Generally, the backplane is permitted to sp...