Quaternary 1T-2MTJ Cell Circuit for a High-Density and a High-Throughput Nonvolatile Bit-Serial CAM

A compact quaternary cell circuit using a single MOS transistor and two magnetic tunnel junction devices (1T-2MTJ) is proposed for a high-density nonvolatile bit-serial content-addressable memory (CAM). The use of quaternary CAM-cell structure makes the search-cycle counts half, which achieves a high-speed search operation. Moreover, the power supply of a CAM word circuit is cut off whenever a mismatched cell is detected during search operation, which greatly reduces the static power dissipation. In fact, the average activation ratio of a 128-bit CAM word circuit is about 2.05 percent. The efficiency of the proposed CAM-cell structure is discussed in comparison with a conventional binary CAM-cell structure under a 0.14 um CMOS/MTJ technology.