Fault-tolerant synthesis using non-uniform redundancy

As process technologies continue to scale into the nanometer regime, devices are becoming significantly more unreliable. Many forms of unreliability manifest as transient faults and can cause intermittent random logic upsets. These logic upsets are often caused by natural radiation (neutrons and alpha particles) or on-chip noise (cross-coupling, supply drop, or flicker noise). This research improves reliability by using non-uniform redundancy. Specifically, we present a dynamic programming algorithm that considers many possible topological redundancies, yet maintains a linear run-time due to efficient pruning of suboptimal solutions. Our algorithm provides designers with a Pareto-optimal set of solutions that trade reliability for area. Compared to existing Triple Modular Redundancy (TMR), we see similar reliability with only 35% area overhead instead of 326%.