Low-power SRAMs power mode control logic: Failure analysis and test solutions

Low-power SRAMs embed power gating mechanisms for reducing static power consumption. Power gating is implemented through power switches for controlling the supply voltage applied to the various memory blocks (array, decoders, I/O logic, etc.). This way, one or more memory blocks can be disconnected from the power supply during a long period of inactivity, thus reducing static power consumption. This paper focuses on low-power SRAMs, and in particular, the power gating mechanisms of core-cells and peripheral circuitry. We provide a detailed analysis based on electrical simulations to characterize the impact of resistive-open defects on the power mode control logic. Based on this analysis, we introduce appropriate fault models that represent the observed faulty behaviors. Finally, we propose an efficient test solution targeting the set of identified fault models.