Fully Integrated AC Coupled Interconnect Using Buried Bumps

Presented is the complete demonstration of an assembled system using AC coupled interconnect (ACCI) and buried solder bumps. In this system, noncontacting input/output (I/O) are created by using half-capacitor plates on both a chip and a substrate, while buried solder bumps are used to provide power/ground distribution and physical alignment of the coupling plates. ACCI using buried bumps is a technology that provides a manufacturable solution for noncontacting I/O signaling by integrating high-density, low inductance power/ground distribution with high-density, high-speed I/O. The demonstration system shows two channels operating simultaneously at 2.5 Gb/s/channel with a bit error rate less than 10^-12, across 5.6 cm of transmission line on a multichip module (MCM). Simple transceiver circuits were designed and fabricated in a 0.35 -mum complementary metal-oxide-semiconductor (CMOS) technology, and for PRBS-127 data at 2.5 Gb/s transmit and receive circuits consumed 10.3 mW and 15.0 mW, respectively. This work illustrates the increasing importance of chip and package co-design for high-performance systems.