Energy-Efficient Nonvolatile Reconfigurable Logic Using Spin Hall Effect-Based Lookup Tables

In this paper, we leverage magnetic tunnel junction (MTJ) devices to design an energy-efficient nonvolatile lookup table (LUT), which utilizes a spin Hall effect (SHE) assisted switching approach for MTJ storage cells. SHE-MTJ characteristics are modeled in Verilog-A based on precise physical equations. Functionality of the proposed SHE-MTJ-based LUT is validated using SPICE simulation. Our proposed SHE-MTJ-based LUT (SHE-LUT) is compared with the most energy-efficient MTJ-based LUT circuits. The obtained results show more than 6%, 37%, and 67% improvement over three previous MTJ-based designs in term of read energy consumption. Moreover, the reconfiguration delay and energy of the proposed design is compared with that of the MTJ-based LUTs which utilize the spin transfer torque (STT) switching approach for reconfiguration. The results exhibit that SHE-LUT can operate at 78% higher clock frequency while achieving at least 21% improvement in terms of reconfiguration energy consumption. The operation-specific clocking mechanisms for managing the SHE-LUT operations are introduced along with detailed analyses concerning tradeoffs. Results are extended to design a 6-input fracturable LUT using SHE-MTJs.