Reducing Aging Effects on Ternary CAM

Ing-Chao LIN  Yen-Han LEE  Sheng-Wei WANG  

IEICE TRANSACTIONS on Electronics   Vol.E99-C   No.7   pp.878-891
Publication Date: 2016/07/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E99.C.878
Type of Manuscript: PAPER
Category: Integrated Electronics
ternary content addressable memory (CAM),  negative bias temperature instability (NBTI),  positive bias temperature instability (PBTI),  reliability,  power gating,  

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Ternary content addressable memory (TCAM), which can store 0, 1, or X in its cells, is widely used to store routing tables in network routers. Negative bias temperature instability (NBTI) and positive bias temperature instability (PBTI), which increase Vth and degrade transistor switching speed, have become major reliability challenges. This study analyzes the signal probability of routing tables. The results show that many cells retain static stress and suffer significant degradation caused by NBTI and PBTI effects. The bit flipping technique is improved and proactive power gating recovery is proposed to mitigate NBTI and PBTI effects. In order to maintain the functionality of TCAM after bit flipping, a novel TCAM cell design is proposed. Simulation results show that compared to the original architecture, the bit flipping technique improves read static noise margin (SNM) for data and mask cells by 16.84% and 29.94%, respectively, and reduces search time degradation by 12.95%. The power gating technique improves read SNM for data and mask cells by 12.31% and 20.92%, respectively, and reduces search time degradation by 17.57%. When both techniques are used, read SNM for data and mask cells is improved by 17.74% and 30.53%, respectively, and search time degradation is reduced by 21.01%.