Clock Skew Scheduling for Soft-Error-Tolerant Sequential Circuits

Soft errors have been a critical reliability concern in nano-scale integrated circuits, especially in sequential circuits where a latched error can be propagated for multiple clock cycles and affect more than one output, more than once. This paper presents an analytical methodology for enhancing the soft error tolerance of sequential circuits. By using clock skew scheduling, we propose to minimize the probability of unwanted transient pulses being latched and also prevent latched errors from propagating through sequential circuits repeatedly. The overall methodology is formulated as a piecewise linear programming problem whose optimal solution can be found by existing mixed integer linear programming solvers. Experiments reveal that 30-40% reduction in the soft error rate for a wide range of benchmarks can be achieved.