TAP-CAM: A Tunable Approximate Matching Engine based on Ferroelectric Content Addressable Memory

Fuente: arXiv
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Hauptverfasser: Ni, Chenyu, Chen, Sijie, Liu, Che-Kai, Liu, Liu, Imani, Mohsen, Kampfe, Thomas, Ni, Kai, Niemier, Michael, Hu, Xiaobo Sharon, Zhuo, Cheng, Yin, Xunzhao
Format: Preprint
Veröffentlicht: 2025
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author Ni, Chenyu
Chen, Sijie
Liu, Che-Kai
Liu, Liu
Imani, Mohsen
Kampfe, Thomas
Ni, Kai
Niemier, Michael
Hu, Xiaobo Sharon
Zhuo, Cheng
Yin, Xunzhao
author_facet Ni, Chenyu
Chen, Sijie
Liu, Che-Kai
Liu, Liu
Imani, Mohsen
Kampfe, Thomas
Ni, Kai
Niemier, Michael
Hu, Xiaobo Sharon
Zhuo, Cheng
Yin, Xunzhao
contents Pattern search is crucial in numerous analytic applications for retrieving data entries akin to the query. Content Addressable Memories (CAMs), an in-memory computing fabric, directly compare input queries with stored entries through embedded comparison logic, facilitating fast parallel pattern search in memory. While conventional CAM designs offer exact match functionality, they are inadequate for meeting the approximate search needs of emerging data-intensive applications. Some recent CAM designs propose approximate matching functions, but they face limitations such as excessively large cell area or the inability to precisely control the degree of approximation. In this paper, we propose TAP-CAM, a novel ferroelectric field effect transistor (FeFET) based ternary CAM (TCAM) capable of both exact and tunable approximate matching. TAP-CAM employs a compact 2FeFET-2R cell structure as the entry storage unit, and similarities in Hamming distances between input queries and stored entries are measured using an evaluation transistor associated with the matchline of CAM array. The operation, robustness and performance of the proposed design at array level have been discussed and evaluated, respectively. We conduct a case study of K-nearest neighbor (KNN) search to benchmark the proposed TAP-CAM at application level. Results demonstrate that compared to 16T CMOS CAM with exact match functionality, TAP-CAM achieves a 16.95x energy improvement, along with a 3.06% accuracy enhancement. Compared to 2FeFET TCAM with approximate match functionality, TAP-CAM achieves a 6.78x energy improvement.
format Preprint
id arxiv_https___arxiv_org_abs_2502_05787
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle TAP-CAM: A Tunable Approximate Matching Engine based on Ferroelectric Content Addressable Memory
Ni, Chenyu
Chen, Sijie
Liu, Che-Kai
Liu, Liu
Imani, Mohsen
Kampfe, Thomas
Ni, Kai
Niemier, Michael
Hu, Xiaobo Sharon
Zhuo, Cheng
Yin, Xunzhao
Emerging Technologies
Pattern search is crucial in numerous analytic applications for retrieving data entries akin to the query. Content Addressable Memories (CAMs), an in-memory computing fabric, directly compare input queries with stored entries through embedded comparison logic, facilitating fast parallel pattern search in memory. While conventional CAM designs offer exact match functionality, they are inadequate for meeting the approximate search needs of emerging data-intensive applications. Some recent CAM designs propose approximate matching functions, but they face limitations such as excessively large cell area or the inability to precisely control the degree of approximation. In this paper, we propose TAP-CAM, a novel ferroelectric field effect transistor (FeFET) based ternary CAM (TCAM) capable of both exact and tunable approximate matching. TAP-CAM employs a compact 2FeFET-2R cell structure as the entry storage unit, and similarities in Hamming distances between input queries and stored entries are measured using an evaluation transistor associated with the matchline of CAM array. The operation, robustness and performance of the proposed design at array level have been discussed and evaluated, respectively. We conduct a case study of K-nearest neighbor (KNN) search to benchmark the proposed TAP-CAM at application level. Results demonstrate that compared to 16T CMOS CAM with exact match functionality, TAP-CAM achieves a 16.95x energy improvement, along with a 3.06% accuracy enhancement. Compared to 2FeFET TCAM with approximate match functionality, TAP-CAM achieves a 6.78x energy improvement.
title TAP-CAM: A Tunable Approximate Matching Engine based on Ferroelectric Content Addressable Memory
topic Emerging Technologies
url https://arxiv.org/abs/2502.05787