A Fast Diagnosis Scheme for Distributed Small Embedded SRAMs

Abstract: This paper proposes a diagnosis scheme aimed at reducing diagnosis time of distributed small embedded SRAMs (e-SRAMs). This scheme improves the one proposed in [A parallel built-in self-diagnostic method for embedded memory buffers, A parallel built-in self-diagnostic method for embedded memory arrays]. The improvements are mainly two-fold. On one hand, the diagnosis of time-consuming Data Retention Faults (DRFs), which is neglected by the diagnosis architecture in [A parallel built-in self-diagnostic method for embedded memory buffers, A parallel built-in self-diagnostic method for embedded memory arrays], is now considered and performed via a DFT technique referred to as the "No Write Recovery Test Mode (NWRTM)". On the other hand, a pair comprising a Serial to Parallel Converter (SPC) and a Parallel to Serial Converter (PSC) is utilized to replace the bi-directional serial interface, to avoid the problems of serial fault masking and defect rate dependent diagnosis. Results from our evaluations show that the proposed diagnosis scheme achieves an increased diagnosis coverage and reduces diagnosis time compared to those obtained in [A parallel built-in self-diagnostic method for embedded memory buffers, A parallel built-in self-diagnostic method for embedded memory arrays], with neglectable extra area cost.