Reconfigurable Radiation-Hardened SRAM Cell Design for Different Radiation Environments

Abstract

This article proposes a novel and effective 14-transistors (14T) reconfigurable radiation-hardened static-random access-memory cell design under the SMIC 65-nm process, featuring a unique memory reconfigurability architecture with two operation modes, namely the high reliability (HR) mode and the triple-time memory (TTM) mode for meeting different radiation environmental requirements. The proposed HR mode provides strong protection of the memory arrays in harsh radiation environments. Compared with the traditional triple modular redundancy (TMR) structure, the proposed HR mode reduces area overhead by 30%, delay by 37%, and power consumption by 16%. The TTM mode uses the enable (EN) circuit to expand the capacity threefold in less harsh radiation environments, avoiding the area wastage caused by the traditional TMR structure. By implementing the two innovative operation modes, the proposed design overcomes the limitations of the traditional TMR structure, reducing area overhead while retaining the radiation hardening capability. In addition, this article presents a mode-switching mechanism composed of a detection circuit and an EN circuit. The detection circuit can detect errors in the reconfigurable architecture. With the proposed mode-switching mechanism, two operation modes can switch in response to different radiation environments. Besides, to ensure the normal operations of the TTM mode in radiation environments, the proposed 14T cell serves as a bitcell in the memory reconfigurable architecture. Compared with typical existing designs, such as radiation-hardened based design, writability enhanced, and dual interlocked storage cell (DICE) cells, the proposed 14T cell design has better delay, critical charge, and higher hold static noise margin.