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Self-timed Circuit Design: from Enigma to Reality

29 May 2015 at IMEC

Asynchronous circuits (also called self-timed circuits) do not rely on a global clock signal and operate using local synchronisation mechanisms such as handshakes. This makes them very different from widely adopted synchronous circuits and promises many benefits, such as inherent tolerance to variations, low power, high performance, and better compositionality. Despite these benefits, asynchronous circuits are not yet widely adopted by industry, mainly because of the difficulties of integrating their design into the standard EDA tool flow.

In this tutorial we will provide a general overview to the state-of-the-art of asynchronous circuit design, will demonstrate existing tool support, and will let participants of the tutorial try these tools by themselves under our guidance. We will also highlight recent success stories, in particular, industrially adopted design flow for “little digital” hardware components – asynchronous microcontrollers that establish the interface between “big digital” synchronous world and mixed-signal/analogue environment. We will show how one can formally design and verify such microcontrollers using freely available open source EDA tools. Finally, we will discuss how these tools can be used for the design of “big digital” asynchronous dataflow pipelines, as well as fully self-timed SRAM, which allows to create systems where processors and memory can seamlessly operate at near-threshold voltages. We will conclude by posing future research and development challenges that are currently on the agenda of the asynchronous community.

It is intended for everyone interested in learning new design paradigms, new software tools and new tricks. Learn how to design digital systems without clock (drop the chains that bind you!)


  • Lectures (90min)
    • Overview of asynchronous circuits
    • Basic building blocks and their composition
    • Building “little digital” controllers
    • Towards “big digital” dataflow circuits
    • Asynchronous memory
    • Synchronization and domain interfacing
    • Glimpse of the future
  • Practicals (90min)
    • Introduction to Workcraft
    • Design of a simple asynchronous circuit
    • Automated circuit synthesis
    • Formal verification
    • Advanced models/tools