Ground-referenced signaling for intra-chip and short-reach chip-to-chip interconnects

While high-speed single-ended signaling maximizes pin and wire utilization within on- and off-chip serial links, problems associated with conventional signaling methods result in energy inefficiencies. Ground-referenced signaling (GRS) solves many of the problems of single-ended signaling systems and can be adapted for signaling across RC-dominated channels and LC transmission lines. The combination of GRS and clock forwarding enables simple but efficient signaling across on-chip communication fabrics, off-chip organic packages, and off-package printed circuit boards. Various methodologies compatible with GRS are presented in this paper, including design considerations and various circuit architectures. Experimental results for multiple generations of GRS-based serial links are presented, which includes a 16Gb/s 170fJ/b/mm on-chip link, a 20Gb/s 0.58pJ/b link across an organic package, and a 25Gb/s 1.17pJ/b link signaling over a printed-circuit board.