Evaluation of different tools for design and fault-injection of asynchronous circuits

Abstract

Asynchronous circuits (ACs) are currently aced out by synchronous circuits (SCs) in industry purposes. Nevertheless there were prominent innovations utilizing ACs in the field of brain-inspired hardware like SpiNNaker, Neurogrid and the TrueNorth. Researchers claim also a theoretical performance advantage of ACs in terms of speed and energy efficiency. However, one handicap when designing ACs is the current lack of tools designated especially to AC design. Often tools originally targeted to SC design are (mis)used. This thesis presents two flows designed especially to AC design. The first one is developed by the Embedded Computing Systems (ECS) group at TU Wien. It is focused on fault-injection experiments at gate level, but provides also Python scripts for high level AC generation. The second one is the Asynchronous Circuit Toolkit (ACT) developed by the asynchronous VLSI and architecture (asyncVLSI) group at YaleUniversity. It aims for a complete coverage of chip design from high level description to fabricable GDSII format. This thesis will extensively present both these flows, and then proceed with their integration into a combined flow. In particular a translation script of the production rule set (PRS) format in its concrete implementation at TU Wien to ACT has been developed. Additionally the fault-injection engine, which is part of the TU Wien flow, has been overhauled to now also support the Prsim simulation software, which is part of the Yale flow. Afterwards, as a proof of concept, for the integrated flow about a million fault-injections have been performed with Modelsim, which was previously without alternative for the TU Wien flow, and Prsim. While one should initially expect the two tools to deliver the same results, mismatches are spotted that could be tracked back to aspects where Modelsim and Prsim operate differently.