SRT Program

2021

1. IEEE TVLSI 2021

   DyTAN: Dynamic Ternary Content Addressable Memory Using Nanoelectromechanical Relays

   Hongtao Zhong^*, Shengjie Cao^*, Li Jiang, Xia An, Vijaykrishnan Narayanan, Yongpan Liu, Huazhong Yang, and Xueqing Li

   IEEE Transactions on Very Large Scale Integration (VLSI) Systems, Nov 2021

   Abs DOI Bib

   Ternary content addressable memory (TCAM) is one type of associative memory and has been widely used in caches, routers, and many other mapping-aware applications. While the conventional SRAM-based TCAM is high speed and bulky, there have been denser but slower and less reliable nonvolatile TCAMs using nonvolatile memory (NVM) devices. Meanwhile, some CMOS TCAMs using dynamic memories have been also proposed. Although dynamic TCAM could be denser than the 16T SRAM TCAM and more reliable than the nonvolatile TCAMs, CMOS dynamic TCAMs still suffer from the row-by-row refresh energy and time overheads. In this article, we propose dynamic TCAM using nanoelectromechanical (NEM) relays (DyTAN), and utilize one-shot refresh (OSR) to solve the memory refresh problem. By exploiting the unique NEM relay characteristics, DyTAN outperforms the existing works in the balance between density, speed, and power efficiency. Compared with the 16T SRAM-based TCAM, the 5T CMOS dynamic TCAM, the 2T2R TCAM, and the 2FeFET TCAM, evaluations show that the proposed DyTAN reduces the write energy by up to 2.3\times , 1.3\times , 131\times , and 13.5\times , and improves the search energy-delay-product (EDP) by up to 12.7\times , 1.7\times , 1.3\times , and 2.8\times , respectively.

   @article{9570131,
     author = {Zhong, Hongtao and Cao, Shengjie and Jiang, Li and An, Xia and Narayanan, Vijaykrishnan and Liu, Yongpan and Yang, Huazhong and Li, Xueqing},
     journal = {IEEE Transactions on Very Large Scale Integration (VLSI) Systems},
     title = {DyTAN: Dynamic Ternary Content Addressable Memory Using Nanoelectromechanical Relays},
     year = {2021},
     volume = {29},
     number = {11},
     pages = {1981-1993},
     keywords = {Relays;Nanoelectromechanical systems;Nonvolatile memory;Logic gates;FeFETs;Electrodes;Very large scale integration;Dynamic ternary content addressable memory (TCAM);low power;(snanoelectromechanical (NEM) relay;TCAM},
     doi = {10.1109/TVLSI.2021.3115622},
     issn = {1557-9999},
     month = nov
   }

2. DATE 2021

   Dynamic Ternary Content-Addressable Memory Is Indeed Promising: Design and Benchmarking Using Nanoelectromechanical Relays

   Hongtao Zhong^*, Shengjie Cao^*, Huazhong Yang, and Xueqing Li

   In 2021 Design, Automation & Test in Europe Conference & Exhibition (DATE), Feb 2021

   Abs DOI Bib

   Ternary content addressable memory (TCAM) has been a critical component in caches, routers, etc., in which density, speed, power efficiency, and reliability are the major design targets. There have been the conventional low-write-power but bulky SRAM-based TCAM design, and also denser but less reliable or higher-write-power TCAM designs using nonvolatile memory (NVM) devices. Meanwhile, some TCAM designs using dynamic memories have been also proposed. Although dynamic design TCAM is denser than CMOS SRAM TCAM and more reliable than NVM TCAM, the conventional row-by-row refresh operations land up with a bottleneck of interference with normal TCAM activities. Therefore, this paper proposes a custom low-power dynamic TCAM using nanoelectromechanical (NEM) relay devices utilizing one-shot refresh to solve the memory refresh problem. By harnessing the unique NEM relay characteristics with a proposed novel cell structure, the proposed TCAM occupies a small footprint of only 3 transistors (with two NEM relays integrated on the top through the back-end-of-line process), which significantly outperforms the density of 16-transistor SRAM-based TCAM. In addition, evaluations show that the proposed TCAM improves the write energy efficiency by 2.31x, 131x, and 13.5x over SRAM, RRAM, and FeFET TCAMs, respectively; The search energy-delay-product is improved by 12.7x, 1.30x, and 2.83x over SRAM, RRAM, and FeFET TCAMs, respectively.

   @inproceedings{9474177,
     author = {Zhong, Hongtao and Cao, Shengjie and Yang, Huazhong and Li, Xueqing},
     booktitle = {2021 Design, Automation & Test in Europe Conference & Exhibition (DATE)},
     title = {Dynamic Ternary Content-Addressable Memory Is Indeed Promising: Design and Benchmarking Using Nanoelectromechanical Relays},
     year = {2021},
     volume = {},
     number = {},
     pages = {1100-1103},
     keywords = {Associative memory;Nanoelectromechanical systems;Nonvolatile memory;Random access memory;Benchmark testing;Reliability engineering;Nanoscale devices;Ternary content addressable memory (TCAM);low-power;NEM relay;beyond-CMOS;dynamic memory},
     doi = {10.23919/DATE51398.2021.9474177},
     issn = {1558-1101},
     month = feb
   }