Hewlett Packard Enterprise Development LP

Cray Incorporated

Andy Becker

Paul T Wildes

Hyunjun Kim

Shawn Utz

Brad Smith

Jim Fitzke

Signal transmission structures within a printed circuit are formed to have reduced loss by making specific accommodations to reduce the surface roughness of an adjacent power plane, and thereby reducing the effects of magnetically induced currents. The power plane structure will retain sufficient surface roughness to accommodate manufacturing operations, while also contributing to reduced signal transmission losses in the adjacent signal transmission structure. The transmission structures thereby being capable of more efficiently transmitting high speed signals without undesired attenuation and loss.

PCB transmission lines having reduced loss

To eliminate signal loss and sources of signal attenuation, a connection methodology is utilized which enables high-speed signals to be directly communicated from particular integrated circuits housed on a printed circuit board, to other locations within a system. More specifically, a signal escape strategy directly connects a high-speed cable to a point on the circuit board which is very close to the integrated circuit itself. A back-side connection methodology is utilized so that electrical signals pass directly from the integrated circuit through a via, to a connection point on the backside of the circuit board. To accommodate this connection, a specially designed interposer and related paddle cards are utilized so the high-speed communication cable can be easily attached.

Direct connection of high speed signals on PCB chip

A printed circuit board includes additional stitching vias placed at strategic location within a connection matrix, which provides additional isolation and further accommodates high-speed communication capabilities. The stitching vias have a variable length or depth, depending on related structures within the circuit board, so as to avoid any interference with underlining escape routing, or alternative signal transmission structures. More specifically, these stitching vias help to eliminate cross-talk in the via field caused by the close proximity of signal carrying structures. Further, differential signal communication is better accommodated based upon this reduction in cross-talk.

PCB with minimized crosstalk

The various structures forming communication paths on a printed circuit board can create several undesired effects, especially when high frequency signals are considered. Non-functional pads created during the manufacturing process have the potential to create an undesired effect, but when the overall collection of non-functional pads are carefully configured, an optimized communication path can be formed. More specifically, by selectively removing some collection of the non-functional pads, the high frequency characteristics of the communication paths can be optimized.

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Eau Claire, WI, United States of America

Andy Becker