Energy Efficient Ultra-Fast Optically Switched Fully Non-Volatile Magnetic Full Adder for Enhanced Side-Channel Attack Resilience

High standby power has become a critical challenge for CMOS circuits below the 90 nm technology node as leakage currents continue to rise. Deeply scaled technologies not only increase power consumption due to subthreshold leakage but also make circuits more vulnerable to side-channel attacks (SCAs), especially leakage power analysis (LPA). Spin-based devices, like magnetic tunnel junctions (MTJs), offer a promising solution with properties such as non-volatility, high endurance, low standby power, and seamless integration with CMOS technology. While switching mechanisms like spin torque transfer (STT) and spin orbit torque (SOT) lower energy consumption, their nanosecond-scale speed is constrained by spin precession. In contrast, all optical switching (AOS) of MTJs enables spin reversal in sub-picosecond timescales, offering faster operation. This paper presents an optically switched fully non-volatile magnetic full-adder (OS-NV-MFA) circuit that uses AOS for input storage in MTJs, achieving both energy-efficiency and SCA-resilience. Results show that the OS-NV-MFA provides 56.11%, 50.78%, and 58.09% improvements in read latency and reduces total power by 76.69%, 53.28%, and 81.97% compared to NV-MFA, STT MFA, and SHE NV-MFA, respectively. Furthermore, the use of configurable and reference MTJs ensures indistinguishable subthreshold leakage currents for '0' and '1' states, enhancing resistance to LPA-based SCAs.