supported by:

AC Coupled Interconnect

Dr. Paul D. Franzon

paulf@ncsu.edu

919.515.7351, fax. 919.515.2285
www.ece.ncsu.edu/erl/faculty/paulf.html

Brief Description

The central thesis in this effort hinges on the recognition that the DC component of a digital signal carries no information, and that non-contacting AC connections can be built a lot denser and simpler than DC connections.  An array of non-contacting structures is inherently denser, more compliant and more mechanically robust than an array of contacting structures.   As shown in the Figures below, these non-contacting structures can be built as capacitor half-plates or opposing inductor spirals of a transformer.  In the capacitive case, the signal is carried through a series capacitor.  In the transformer case, by a small signal transformer.  By imposing direct contacts only where DC signal transfers are needed, this approach will allow very high density interconnects to be realized and alleviate the compliance and rework problems encountered in other high density interconnect technologies. 

The main goal of this project is to complete a series of key demonstrations.  The demonstration of complete single-chip package systems, capable of 75 mm I/O pitch, 5 Gbps rate per pin, 20 mW power budget and low bit error rates over links between 10 cm and 120 cm in length.  The longer link includes low-cost connectors with pin pitches below 250 mm.

Key Activities towards this goal include the following:

• Design and implementation of the physical structures, including single and multi-chip packages, solder bumping, and connector design.  Much of this, especially the solder bumping, is in performed collaboration with MCNC-RDI.

• Design of I/O circuits, including pre-emphasis, equalization.

• Development of new coding schemes, and application of existing ones.

Selected Publications and Talks

• Invited Paper at the 2002 Custom Integrated Circuits Conference :    Paper     Talk

Publications

• S. E. Mick, J. M. Wilson, and P. Franzon, “4 Gbps AC Coupled Interconnection,” (invited paper), IEEE Custom Integrated Circuits Conference, May 12-16, 2002, pp. 133-140.

  S. Mick, P. Franozn, A. Huffman, Packaging Technology for AC Coupled Interconnection, IEEE Flip-Chip Conference, July 2002.

  S.E. Mick, L. Luo, J.M. Wilson, P.D. Franzon, “Buried Solder Bump Connections for High-Density Capacitive Coupling,” IEEE Electrical Performance on Electornic Packaging, October, 2002.