A Highly Compact Nonvolatile Ternary Content Addressable Memory (TCAM) With Ultralow Power and 200-ps Search Operation
Xianggao Wang, Yiming Qu, Fan Yang, Liang Zhao, Choonghyun Lee, Yi Zhao
Abstract
In this work, we developed a nonvolatile ternary content addressable memory (TCAM) with a cell size of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.01~\mu \text{m}^{{2}}$ </tex-math></inline-formula> utilizing the Ge-based memory diode (MD), which has the most area-efficient TCAM design reported. The MDs have a high current ratio between ON and OFF states and a large rectifying ratio, showing the potential usage in large-dimension TCAM arrays. Besides, the functionality of parallel search was demonstrated with a 2-bit MD-TCAM array by experiment, and the electrical characterization showed expected results. With the help of the sub-ns ultrafast measurement system, it is confirmed that the search energy of MD-TCAM could reach as low as 1.0 fJ/bit/mismatch, and one search operation can be performed within 200 ps. Furthermore, the circuit-level simulation results verified that the MD-TCAM developed in this study shows good performance in 128-bit parallel searching, which is promising for the ultrafast and low-power data search applications in the coming IoT era.