Word-line power supply selector for stability improvement of embedded SRAMs in high reliability applications

Embedded SRAM yield dominates the overall ASIC yield, therefore the methodologies centered on improving SRAM cell stability will be introduced in the design as a mandatory. Word-line voltage modulation has showed that it is possible to improve cell stability during access operations. The high variability of physical and performance parameters introduce the need to adopt adaptable solutions to adequately improve SRAM cell stability. In this work, we present a wordline voltage selector circuit designed to modulate power-supply word-line voltage at each individual embedded SRAM block. The final area overhead is minimal and several strategies can be implemented with the embedded SRAM allowing adjust wordline voltage value during the life of ASIC, taking into account different operation, aging and degradations effects.