40 Gbit/s "fish ladder" signal path and connectorized signal path in ceramic and organic packages for OC768 applications

IBM is providing robust packaging solutions for high speed networking chips utilizing Silicon Germanium (SiGe) and CMOS technology. Recently, while still using current packaging design ground rules needed to yield a manufacturable product, a novel "fish ladder" transmission line structure that exits through the 2nd level Package Ball Grid Array (BGA) onto a Printed Circuit Board (PCB) was introduced into the package. The benefit afforded by this structure allows the system designer the ability to route high speed signal traces directly through to the PCB where highly reliable Surface Mount Technology (SMT) connectors can be used, thereby eliminating the need for more costly and assembly intensive techniques for connectors on the package. The "fish ladder" for the first time can support 40 Gbit/s and 50 Gbit/s transmission speeds. Herein is described the "fish ladder" structure, the electrical modeling of the structure up to 40 GHz in both IBM's alumina ceramic and SLC/spl trade/ (Surface Laminar Circuit) organic package. Also the S parameter measurement of the assembled package up to 45 GHz demonstrating the performance is included.