A dynamic CAM - based on a one-hot-spot block code - for millions-entry lookup

摘要

With the aim of realizing large-scale and low-power CAMs for millions-entry lookup, the authors have devised a one-hot-spot block code and developed three circuit techniques. The proposed code efficiently stores IP addresses and reduces the entry count down by 52% on average. The first and second techniques, a hierarchical match-line structure and an on-chip entry compression/extraction scheme, enable the proposed code to be applied to our new CAM. In addition to the second technique, the third technique, a search-depth control scheme, restricts activating unneeded search lines and reduces power consumption down by 45%. In the case of 72-bit data, the proposed CAM, using a stacked capacitor, effectively achieves 1.5 million entries, which is six times larger than that of a conventional static TCAM.