Design of a Nine-Transistor/Two-Magnetic-Tunnel-Junction-Cell-Based Low-Energy Nonvolatile Ternary Content-Addressable Memory

Abstract

Towards a low search-energy nonvolatile ternary content-addressable memory (TCAM), we propose a novel nine-transistor/two-magnetic-tunnel-junction (9T–2MTJ) nonvolatile TCAM cell circuit with a high-speed accessibility. Since critical path for switching in the TCAM cell circuit is only a single metal-oxide-semiconductor (MOS) transistor, switching delay of the TCAM word circuit is minimized. As a result, the worst-case switching delay of 0.22 ns is achieved in a 144-bit word circuit under a 90 nm complementary MOS (CMOS)/MTJ technology, which is about 2.6 times faster than that of a conventional CMOS-based TCAM. In order to minimize the active power dissipation in the proposed TCAM, a multi-level segmented match-line scheme that maximally brings inessential cells to standby state is also applied to the 9T–2MTJ-cell-based word circuit. Finally, low search-energy of 0.73 fJ/bit/search is achieved in a 144-bit × 256-word nonvolatile TCAM together with eliminating standby power using nonvolatility.