Ripple-precharge tcam a low-power solution for network search engines. iccd

A novel low power ripple-precharge Ternary CAM (RP-TCAM) architecture is proposed for applications in longest prefix matching tasks. The main motivation behind this research is to reduce the dynamic power consumption in TCAM due to frequent charging and discharging of the highly capacitive match line. This issue is addressed by exploiting the fact that when we compare only the first four bits of incoming packet’s destination address we can identify up to 80 % mismatches in the forwarding table. A selective precharge scheme was devised exploiting the above fact wherein the match line is charged only when there is an exact match in the first four bits of TCAM word, thereby significantly reducing the number of transitions in the match line. The parasitics for simulation were extracted from the layout implemented for a 64¢32 RP-TCAM architectur

Reduce TCAM Static Power Consumption Using Mask-Gating Method

本論文中，我們提出一個以遮罩控制為基礎的三元內容定址記憶體（Ternary Content Addressable Memories，TCAM）架構，以達到降低靜態功率消耗的目的。相較於傳統TCAM架構的設計，我們提出的改進之處是利用了遮罩資料的連續特性，並使用分段和遮罩資料前後控制的方法減少遮罩記憶體正常運作的個數，用以達到節省靜態功率消耗的目的。本設計是使用UMC 90nm的製程來設計並驗證電路，對32b*128的TCAM陣列而言，實驗模擬結果在1.0V的供應電壓下，大約能夠節省23%~30%的靜態功率消耗。This thesis proposes a low leakage TCAM design which uses mask power gating technique to reduce the static power dissipated in the mask SRAM. This reduction depends on continuous TCAM mask patterns where mask bits in a segment are all 1 or 0 except for the segment located at the boundary of the TCAM mask word. Our design exploits the fact where only mask bits of the boundary segment are active to significantly reduce the number of active mask cells. Using UMC 90 nm CMOS process with 1.0V supply voltage, the simulation results show more than 30% static power can be reduced with size of 32b*128 compared to the traditional TCAM design.目錄 摘要 I 表格目錄 VII 圖目錄 VIII 1、 簡介 1 2、 傳統三元內容定址記憶體架構設計（Traditional Ternary CAM Design） 7 2.1 傳統TCAM的運作 7 2.2 TCAM的搜尋行為 15 2.3 TCAM的動態功率消耗分析 16 2.4 TCAM的靜態功率消耗分析 20 2.5 SRAM的控制技術及靜態功率消耗分析 23 2.5 遮罩資料的連續特性（Continuous feature of mask data） 26 2.6 相關研究 28 I. Ripple-Precharge TCAM：A Low-Power Solution for Network Search Engines 28 II. “Green” Micro-Architecture and Circuit Co-design For Ternary Content Addressable Memory 30 3、 遮罩控制低功率三元內容定址記憶體設計（Mask-Gating Ternary CAM Design） 32 3.1 遮罩資料的分段（Partition Mask Data） 33 3.2 MG-TCAM的結構（Structure of mask-gating TCAM） 37 3.3 區段內固定長度的分割方法（Partition methods with fixed length） 42 3.4 Prefix長度的分佈和VOPM（Prefix length distribution and VOPM） 44 4、 實驗結果分析（Simulation Results Analysis） 48 4.1 模擬時序圖 48 4.2 靜態功率消耗分析（Static Power Consumption） 56 4.3 效能分析（Search delay） 60 5、 結論 62 6、 未來展望 63 7、 參考文獻 6