Reliability Evaluation of Voters for Fault Tolerant Approximate Systems

This work presents a study on the reliability of voters for approximate fault tolerant systems in the context of single event effects. A first case study analyses different topologies of single-bit majority voters for logic circuits by means of fault injection by simulation. In these simulations a previous analysis is performed identifying the critical diffusion areas of the physical implementation according to the voter input vector. Additionally, as second case study, practical heavy ion experiments on different architectures of software-based approximate voters for mixed-signal applications are also presented, and the cross section of each voter is evaluated. The system comprising the voter was irradiated in two distinct experiments with an ¹⁶O ion beam, producing an effective $LET$ at the active region of 5.5 MeV/mg/cm². Results of both case-studies allow identifying the most tolerant voter architectures (among the studied ones) for approximate computing applications under single event effects.