Impacts of NBTI and PBTI effects on ternary CAM

Abstract

Ternary content addressable memory (TCAM), which can store 0, 1 and X in its cells, is widely used to store routing tables in network routers. Meanwhile, NBTI (Negative Bias Temperature Instability) and PBTI (Positive Biased Temperature Instability), which increase Vth and degrade transistor switching speed, have become major reliability challenges. In this paper, we propose a novel TCAM architecture to reduce BTI degradation using a bit-flipping technique. This novel TCAM architecture ensures the correctness of read, write and search operations. We also analyze the signal probabilities of TCAM cells, and demonstrate that the bit-flipping technique can balance signal probabilities. By using the bit-flipping technique, 76.40% of the data cells under investigation were found to have signal probabilities close to 50%, which is 62.80% higher than the original architecture. In addition, 92.60% of the mask cells had signal probabilities close to 50%, which is 91.20% higher than the original architecture. When considering the overhead of the bit-flipping technique, the best flipping frequency is once a day.