A new SBST algorithm for testing the register file of VLIW processors

Feature size reduction drastically influences permanent faults occurrence in nanometer technology devices. Among the various test techniques, Software-Based Self-Test (SBST) approaches have been demonstrated to be an effective solution for detecting logic defects, although achieving complete fault coverage is a challenging issue due to the functional-based nature of this methodology. When VLIW processors are considered, standard processor-oriented SBST approaches result deficient since not able to cope with most of the failures affecting VLIW multiple parallel domains. In this paper we present a novel SBST algorithm specifically oriented to test the register files of VLIW processors. In particular, our algorithm addresses the cross-bar switch architecture of the VLIW register file by completely covering the intrinsic faults generated between the multiple computational domains. Fault simulation campaigns comparing previously developed methods with our solution demonstrate its effectiveness. The results show that the developed algorithm achieves a 97.12% fault coverage which is about twice better than previously developed SBST algorithms. Further advantages of our solution are the limited overhead in terms of execution cycles and memory occupation.