1. [Publications](/publications) 2. A 0.54 pJ/b 20 Gb/s Ground-Referenced Single-Ended Short-Reach Serial Link in 28 nm CMOS for Advanced Packaging Applications # A 0.54 pJ/b 20 Gb/s Ground-Referenced Single-Ended Short-Reach Serial Link in 28 nm CMOS for Advanced Packaging Applications ![](/sites/default/files/styles/wide/public/pubs/2013-12_A-0-54/Capture.PNG?itok=sPqGeqni) High-speed signaling over high density interconnect on organic package substrates or silicon interposers offers an attractive solution to the off-chip bandwidth limitation problem faced in modern digital systems. In this paper, we describe a signaling system co-designed with the interconnect to take advantage of the characteristics of this environment to enable a high-speed, low area, and low-power die to die link. Ground-Referenced Signaling (GRS) is a single-ended signaling system that eliminates the problems traditionally associated with single-ended design by using the ground plane as the reference and signaling above and below ground. This design employs a novel charge pump driver that additionally eliminates the issue of simultaneous switching noise with data independent current consumption. Silicon measurements from a test chip implementing two 16-lane links, with forwarded clocks, in a standard 28nm process demonstrate 20Gb/s operation at 0.54pJ/bit over 4.5mm organic substrate channels at a nominal 0.9V power supply voltage. Timing margins at the receiver are >0.3UI at a BER of <10^-12 . We estimate BER < 10^-25 at the eye center. ## Authors John Poulton (NVIDIA) [William Dally](/person/william-dally) [Xi Chen](/person/xi-chen) John Eyles (NVIDIA) [Trey Greer](/person/trey-greer) [Stephen Tell](/person/stephen-tell) [John Wilson](/person/john-wilson) [Tom Gray](/person/tom-gray) ## Publication Date Sunday, December 1, 2013 ## Published in [Journal of Solid State Circuits](http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=6601723) ## Research Area [Circuits and VLSI Design](/research-area/circuits) ## Copyright This material is posted here with permission of the IEEE. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to .