A Highly Compact Nonvolatile Ternary Content Addressable Memory (TCAM) With Ultralow Power and 200-ps Search Operation

In this work, we developed a nonvolatile ternary content addressable memory (TCAM) with a cell size of $0.01~\mu \text{m}^{{2}}$ 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.