Synchronizer-Free Digital Link Controller

Johannes Bund, Matthias Fugger, Christoph Lenzen, Moti Medina

Research output: Contribution to journalArticlepeer-review

Abstract

This work presents a producer-consumer link between two independent clock domains. The link allows for metastability-free, low-latency, high-throughput communication by slight adjustments to the clock frequencies of the producer and consumer domains steered by a controller circuit. Any such controller cannot deterministically avoid, detect, nor resolve metastability. Typically, this is addressed by synchronizers, incurring a larger dead time in the control loop. We follow the approach of Friedrichs et al. (TC 2018) who proposed metastability-containing circuits. The result is a simple control circuit that may become metastable, yet deterministically avoids buffer underrun or overflow. More specifically, the controller output may become metastable, but this may only affect oscillator speeds within specific bounds. In contrast, communication is guaranteed to remain metastability-free. We formally prove correctness of the producer-consumer link and a possible implementation that has only small overhead. With SPICE simulations of the proposed implementation we further substantiate our claims. The simulation uses 65nm process running at roughly 2GHz.

Original languageEnglish
Article number9085899
Pages (from-to)3562-3573
Number of pages12
JournalIEEE Transactions on Circuits and Systems I: Regular Papers
Volume67
Issue number10
DOIs
StatePublished - 1 Oct 2020

Keywords

  • Producer-consumer link
  • continuous processes
  • digital controllers
  • metastability-containing mixed signal control loop
  • metastability-free

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