Low complexity burst error correcting codes to correct MBUs in SRAMs

Abstract

Multiple bit upsets (MBUs) caused by high energy radiation is the most common source of soft errors in static random-access memories (SRAMs) affecting multiple cells. Burst error correcting Hamming codes have most commonly been used to correct MBUs in SRAM cell since they have low redundancy and low decoder latency. But with technology scaling, the number of bits being affected increases, thus requiring a need for increasing the burst size that can be corrected. However, this is a problem because it increases the number of syndromes exponentially thus increasing the decoder complexity exponentially as well. In this paper, a new burst error correcting code based on Hamming codes is proposed which allows much better scaling of decoder complexity as the burst size is increased. For larger burst sizes, it can provide significantly smaller and faster decoders than existing methods thus providing higher reliability at an affordable cost. Moreover, there is frequently no increase in the number of check bits or a very minimal increase in comparison with existing methods. A general construction and decoding methodology for the new codes is proposed. Experimental results are presented comparing the decoder complexity for the proposed codes with conventional burst error correcting Hamming codes demonstrating the significant improvements that can be achieved.