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1. Design and Evaluation of a Spintronic In-Memory Processing Platform for Non-Volatile Data Encryption

   https://doi.org/10.1109/TCAD.2017.2774291  

   Angizi, Shaahin ; He, Zhezhi ; Bagherzadeh, Nader ; Fan, Deliang ( November 2017 , IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems)

   In this paper, we propose an energy-efficient reconfigurable platform for in-memory processing based on novel 4-terminal spin Hall effect-driven domain wall motion devices that could be employed as both non-volatile memory cell and in-memory logic unit. The proposed designs lead to unity of memory and logic. The device to system level simulation results show that, with 28% area increase in memory structure, the proposed in-memory processing platform achieves a write energy ~15.6 fJ/bit with 79% reduction compared to that of SOT-MRAM counterpart while keeping the identical 1ns writing speed. In addition, the proposed in-memory logic scheme improves the operating energy by 61.3%, as compared with the recent non-volatile in-memory logic designs. An extensive reliability analysis is also performed over the proposed circuits. We employ Advanced Encryption Standard (AES) algorithm as a case study to elucidate the efficiency of the proposed platform at application level. Simulation results exhibit that the proposed platform can show up to 75.7% and 30.4% lower energy consumption compared to CMOS-ASIC and recent pipelined domain wall (DW) AES implementations, respectively. In addition, the AES Energy-Delay Product (EDP) can show 15.1% and 6.1% improvements compared to the DW-AES and CMOS-ASIC implementations, respectively.
2. PIMA-logic: a novel processing-in-memory architecture for highly flexible and energy-efficient logic computation

   https://doi.org/10.1145/3195970.3196092  

   Angizi, Shaahin ; He, Zhezhi ; Fan, Deliang ( June 2018 , 55th Annual Design Automation Conference)

   In this paper, we propose PIMA-Logic, as a novel Processing-in-Memory Architecture for highly flexible and efficient Logic computation. Insteadof integrating complex logic units in cost-sensitive memory, PIMA-Logic exploits a hardware-friendly approach to implement Boolean logic functions between operands either located in the same row or the same column within entire memory arrays. Furthermore, it can efficiently process more complex logic functions between multiple operands to further reduce the latency and power-hungry data movement. The proposed architecture is developed based on Spin Orbit Torque Magnetic Random Access Memory (SOT-MRAM) array and it can simultaneously work as a non-volatile memory and a reconfigurable in-memory logic. The device-to-architecture co-simulation results show that PIMA-Logic can achieve up to 56% and 31.6% improvements with respect to overall energy and delay on combinational logic benchmarks compared to recent Pinatubo architecture. We further implement an in-memory data encryption engine based on PIMA-Logic as a case study. With AES application, it shows 77.2% and 21% lower energy consumption compared to CMOS-ASIC and recent RIMPA implementation, respectively.
3. Cascaded Logic Gates Based on High-Performance Ambipolar Dual-Gate WSe ₂ Thin Film Transistors

   https://doi.org/10.1021/acsnano.3c03932  

   Li, Xintong ; Zhou, Peng ; Hu, Xuan ; Rivers, Ethan ; Watanabe, Kenji ; Taniguchi, Takashi ; Akinwande, Deji ; Friedman, Joseph S. ; Incorvia, Jean Anne ( June 2023 , ACS Nano)

   Ambipolar dual-gate transistors based on low-dimensional materials, such as graphene, carbon nanotubes, black phosphorus, and certain transition metal dichalcogenides (TMDs), enable reconfigurable logic circuits with a suppressed off-state current. These circuits achieve the same logical output as complementary metal–oxide semiconductor (CMOS) with fewer transistors and offer greater flexibility in design. The primary challenge lies in the cascadability and power consumption of these logic gates with static CMOS-like connections. In this article, high-performance ambipolar dual-gate transistors based on tungsten diselenide (WSe2) are fabricated. A high on–off ratio of 108 and 106, a low off-state current of 100 to 300 fA, a negligible hysteresis, and an ideal subthreshold swing of 62 and 63 mV/dec are measured in the p- and n-type transport, respectively. We demonstrate cascadable and cascaded logic gates using ambipolar TMD transistors with minimal static power consumption, including inverters, XOR, NAND, NOR, and buffers made by cascaded inverters. A thorough study of both the control gate and the polarity gate behavior is conducted. The noise margin of the logic gates is measured and analyzed. The large noise margin enables the implementation of VT-drop circuits, a type of logic with reduced transistor number and simplified circuit design. Finally, the speed performancemore »of the VT-drop and other circuits built by dual-gate devices is qualitatively analyzed. This work makes advancements in the field of ambipolar dual-gate TMD transistors, showing their potential for low-power, high-speed, and more flexible logic circuits.« less
4. Spin-Orbit Torque Devices for Hardware Security: From Deterministic to Probabilistic Regime

   https://doi.org/10.1109/TCAD.2019.2917856  

   Patnaik, Satwik ; Rangarajan, Nikhil ; Knechtel, Johann ; Sinanoglu, Ozgur ; Rakheja, Shaloo ( May 2019 , IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems)

   Protecting intellectual property (IP) has become a serious challenge for chip designers. Most countermeasures are tailored for CMOS integration and tend to incur excessive overheads, resulting from additional circuitry or device-level modifications. On the other hand, power density is a critical concern for sub-50 nm nodes, necessitating alternate design concepts. Although initially tailored for error-tolerant applications, imprecise computing has gained traction as a general-purpose design technique. Emerging devices are currently being explored to implement ultra-low-power circuits for inexact computing applications. In this paper, we quantify the security threats of imprecise computing using emerging devices. More specifically, we leverage the innate polymorphism and tunable stochastic behavior of spin-orbit torque (SOT) devices, particularly, the giant spin-Hall effect (GSHE) switch. We enable IP protection (by means of logic locking and camouflaging) simultaneously for deterministic and probabilistic computing, directly at the GSHE device level. We conduct a comprehensive security analysis using state-of-the-art Boolean satisfiability (SAT) attacks; this study demonstrates the superior resilience of our GSHE primitive when tailored for deterministic computing. We also demonstrate how probabilistic computing can thwart most, if not all, existing SAT attacks. Based on this finding, we propose an attack scheme called probabilistic SAT (PSAT) which can bypass the defensemore »offered by logic locking and camouflaging for imprecise computing schemes. Further, we illustrate how careful application of our GSHE primitive can remain secure even on the application of the PSAT attack. Finally, we also discuss side-channel attacks and invasive monitoring, which are arguably even more concerning threats than SAT attacks.« less
5. Energy-Efficient Adiabatic Circuits Using Transistor-Level Monolithic 3D Integration

   Miketic, Ivan ; Salman, Emre ( September 2020 , IEEE International System-on-Chip Conference (SOCC))

   Charge-recycling adiabatic circuits are recently receiving increased attention due to both high energy-efficiency and higher resistance against side-channel attacks. These characteristics make adiabatic circuits a promising technique for Internet-of-things based applications. One of the important limitations of adiabatic logic is the higher intra-cell interconnect capacitance due to differential outputs and cross-coupled pMOS transistors. Since energy consumption has quadratic dependence on capacitance in adiabatic circuits (unlike conventional static CMOS where dependence is linear), higher interconnect capacitance significantly degrades the overall power savings that can be achieved by adiabatic logic, particularly in nanoscale technologies. In this paper, monolithic 3D integrated adiabatic circuits are introduced where transistor-level monolithic 3D technology is used to implement adiabatic gates. A 45 nm two-tier Mono3D PDK is used to demonstrate the proposed approach. Monolithic inter-tier vias are leveraged to significantly reduce parasitic interconnect capacitance, achieving up to 47% reduction in power-delay product as compared to 2D adiabatic circuits in a 45 nm technology node.