A Novel Non-Voltatile Magnetic Majority Gate with Voltage-Gated Spin-Orbit Torque Magnetic Tunnel Junction Cascaded in Series for Low Power and High Reliability

This paper proposes a novel non-volatile magnetic majority gate (NVMMG), which employs the advanced emerging voltage-gated spin-orbit torque magnetic tunnel junction (VGSOT-MTJ) to store its input logic operands. To achieve high reliability, one differential memory cell is proposed, which is mainly composed of five access transistors and two VGSOT-MTJs in a complementary state to store a 1-bit input logic operand, called 5T-2MTJ cell. To achieve low power, the proposed NVMMG is designed by cascading multiple 5T-2MTJ cells in series. In this way, the output of the proposed NVMMG can be characterized by the resistance sum of these cascaded VGSOT-MTJs with no access transistor, thereby further im-proving its reliability. By using a physic-based VGSOT-MTJ compact model and a commercial CMOS 40 nm design kit, we have demonstrated the functionality of the proposed NVMMG and evaluated its performance. Simulation results show that for its logic operation with three inputs, it can achieve a fast speed of
$\sim 1.11$
ns and low energy dissipation of
$\sim 4.07\text{fJ}$
. For its write operation, it can achieve a fast write speed of
$\sim 1$
ns and low energy dissipation of
$\sim 10.66\text{fJ}$
. Monte-Carlo simulation results show that the proposed NVMMG can achieve no error rate when the TMR exceeds 240%.