Exploring the state dependent SET sensitivity of asynchronous logic - The muller-pipeline example

Abstract

Asynchronous circuits exhibit considerable advantages over their synchronous counterparts, like lower dynamic power and inherent variation tolerance, which makes them increasingly interesting. Their fault-tolerance behavior, however, is not yet fully explored. In particular, temporal masking, as seen with synchronous circuits, seems to be completely nonexistent in asynchronous logic. Instead, there seem to be other masking mechanisms in the control structure that establish an extra barrier for transient fault propagation. In this paper we will explore these masking mechanisms in a qualitative as well as quantitative manner. To this end we first analyze the behavior of a Muller C-element, one fundamental building block in asynchronous designs. In a next step we evaluate the behavior of a chain of these elements, forming a so-called Muller pipeline, the basic control structure of many asynchronous designs, under transient faults. To validate our theoretical findings we inject radiation induced single event transients (SETs) in an extensive simulation campaign. The results show that the SET susceptibility of the Muller pipeline is indeed state dependent. This knowledge can be leveraged to improve, e.g., the radiation hardness of asynchronous circuits by preferring the more robust states in their design wherever possible.

Design and tool flow of a reconfigurable asynchronous neural network accelerator

“…In some event-driven applications, such as Spiking Neural Networks (SNN), asynchronous circuits can control circuits in an event-driven manner more naturally than clock gating. As a result, asynchronous logic has been advocated as a means of reducing power consumption in many applications [11,12] . IBMs TrueNorth, which successfully implements SNN on a chip, has a low power requirement of 65 mW [13] , and the energy consumption in every state change of the neuron in Intel's Loihi is only 52-81 pJ [14] .…”