Load balancing in a hybrid ATPG environment

The problem of balancing the computational load between fault simulation and conventional ATPG (automatic test program generation) is treated. A rule for switching from probabilistic to deterministic test pattern computation is derived. The criterion is based on a model of monitoring of the simulation process and on an online estimation of the fault detection probabilities. Using these probabilities and the operation characteristics of the ATPG program, one can decide whether it is more efficient to continue fault simulation or to proceed with algorithmic test pattern computation. A prototype of the hybrid ATPG system was implemented on an Apollo DN3000. Compared to a conventional ATPG system, better coverage and shorter generation times were obtained