William N Appel

US Patent:

56382871, Jun 10, 1997

Filed:

Aug 5, 1996

Appl. No.:

8/689186

Inventors:

William D. Appel - Boca Raton FL

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

H04B 1500

US Classification:

364488

Abstract:

Packaged signal routing circuits (e. g. on printed circuit cards or boards), route pulse signals with very short rise times from a lossy driver to multiple devices. In these routing circuits, a complex network of conductors branches from a common junction adjacent the driver output into multiple (in the disclosed embodiment, three) conduction paths of unequal length. In accordance with the invention, the internal impedance of the driver is matched to the aggregate charateristic impedance of the branch paths, and a lossless compensating circuit is attached to a shortest branch path. The compensating circuit is designed to transfer signal reflections of predetermined form to the branching junction at the driver via the shortest branch. Without the compensating circuit, reflections presented to the branching junction from the shortest branch are dissimilar to reflections presented to that junction from other branch paths. Consequently, re-reflections return from the junction to the branches, causing distortions in signals sensed at the devices.

US Patent:

55440479, Aug 6, 1996

Filed:

Dec 29, 1993

Appl. No.:

8/175327

Inventors:

William D. Appel - Boca Raton FL

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

H04B 1500

US Classification:

364488

Abstract:

Packaged signal muting circuits (e. g. on primed circuit cards or boards), route pulse signals with very short rise times from a lossy driver to multiple devices. In these routing circuits, a complex network of conductors branches from a common junction adjacent the driver output into multiple (in the disclosed embodiment, three) conduction paths of unequal length. In accordance with the invention, the internal impedance of the driver is matched to the aggregate characteristic impedance of the branch paths, and a loss less compensating circuit is attached to a shortest branch path. The compensating circuit is designed to transfer signal reflections of predetermined form to the branching junction at the driver via the shortest branch.