PALS: Plesiochronous and Locally Synchronous Systems

Johannes Bund, Matthias Fugger, Christoph Lenzen, Moti Medina, Will Rosenbaum

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review


Consider an arbitrary network of communicating modules on a chip, each requiring a local signal telling it when to execute a computational step. There are three common solutions to generating such a local clock signal: (i) by deriving it from a single, central clock source, (ii) by local, free-running oscillators, or (iii) by handshaking between neighboring modules. Conceptually, each of these solutions is the result of a perceived dichotomy in which (sub)systems are either clocked or fully asynchronous, suggesting that the designer's choice is limited to deciding where to draw the line between synchronous and asynchronous design. In contrast, we take the view that the better question to ask is how synchronous the system can and should be. Based on a distributed clock synchronization algorithm, we present a novel design providing modules with local clocks whose frequency bounds are almost as good as those of corresponding free-running oscillators, yet neighboring modules are guaranteed to have a phase offset substantially smaller than one clock cycle. Concretely, parameters obtained from a 15 nm ASIC implementation running at 2 GHz yield mathematical worst-case bounds of 30ps on phase offset for a 32\times 32 node grid network.

Original languageEnglish
Title of host publicationProceedings - 2020 26th IEEE International Symposium on Asynchronous Circuits and Systems, ASYNC 2020
PublisherIEEE Computer Society
Number of pages8
ISBN (Electronic)9781728154954
StatePublished - 1 May 2020
Externally publishedYes
Event26th IEEE International Symposium on Asynchronous Circuits and Systems, ASYNC 2020 - Snowbird, United States
Duration: 17 May 202020 May 2020

Publication series

NameProceedings - International Symposium on Asynchronous Circuits and Systems


Conference26th IEEE International Symposium on Asynchronous Circuits and Systems, ASYNC 2020
Country/TerritoryUnited States


  • GALS
  • clocking
  • gradient clock synchronization

All Science Journal Classification (ASJC) codes

  • Electrical and Electronic Engineering


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