New Mix codes for multiple bit upsets mitigation in fault-secure memories

Nowadays, multibit error correction codes (MECCs) are effective approaches to mitigate multiple bit upsets (MBUs) in memories. As technology scales, combinational circuits have become more susceptible to radiation induced single event transient (SET). Therefore, transient faults in encoding and decoding circuits are more frequent than before. Firstly, this paper proposes a new MECC, which is called Mix code, to mitigate MBUs in fault-secure memories. Considering the structure characteristic of MECC, Euclidean Geometry Low Density Parity Check (EG-LDPC) codes and Hamming codes are combined in the proposed Mix codes to protect memories against MBUs with low redundancy overheads. Then, the fault-secure scheme is presented, which can tolerate transient faults in both the storage cell and the encoding and decoding circuits. The proposed fault-secure scheme has remarkably lower redundancy overheads than the existing fault-secure schemes. Furthermore, the proposed scheme is suitable for ordinary accessed data width (e.g., 2n bits) between system bus and memory. Finally, the proposed scheme has been implemented in Verilog and validated through a wide set of simulations. The experiment results reveal that the proposed scheme can effectively mitigate multiple errors in whole memory systems. They can not only reduce the redundancy overheads of the storage array but also improve the performance of MECC circuits in fault-secure memory systems.