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Spin transfer torque magnetic random access memory (STT-MRAM) offers a promising solution for low-power and high-density memory due to its compatibility with CMOS, higher density, scalable nature, and non-volatility. However, the higher energy required to write bit cells has remained a key challenge for its adaptation into battery-operated smart handheld devices. The existing low-energy writing solutions require additional complex control logic mechanisms, further constraining the available area. In this research, we propose a solution to design energy-efficient write circuits by incorporating two techniques together. First, we propose the sinusoidal power clocking mechanism replacing the DC power supply in the conventional CMOS design. Second, we propose three lookup table (LUT)-based control logic circuits and one write circuit to reduce the area and further minimize energy dissipation. The experimental results are verified over the case study implementations of 4×4 STT-MRAM macro designed using bit cell configurations: i) one transistor and one magnetic tunnel junction (MTJ) (1T-1MTJ) and ii) four transistors and two MTJs (4T-2MTJ). The post-layout simulation for the frequency range from 250 kHz to 6.25 MHz shows that the write circuit, which uses the proposed LUT-based control logic circuits and a write driver with a sinusoidal power supply, achieves more than a 65.05% average energy saving compared to the CMOS counterpart. Furthermore, the write circuit, which uses the proposed 6T write driver with the sinusoidal power supply, shows an improvement in energy saving by more than 70.60% compared to the CMOS counterpart. We also verified that the energy-saving performance remains relatively consistent with the change in temperature and the tunneling magnetoresistance (TMR) ratio. 

Designing a low-energy and secure lightweight cryptographic coprocessor is the primary design constraint for modern wireless Implantable Medical Devices (IMDs). The lightweight cryptographic ciphers are the preferred cryptographic solution for low-energy encryption. This article proposes 2-SPGAL, the 2-phase sinusoidal clocking implementation of Symmetric Pass Gate Adiabatic Logic (SPGAL) for IMDs. The proposed 2-SPGAL is energy-efficient and secure against the Correlation Power Analysis (CPA) attack. The proposed 2-SPGAL was evaluated with the integration of synchronous resonant Power Clock Generators (PCGs): (i) 2N2P-PCG, and (ii) 2N-PCG. The case study implementation of one round of PRESENT-80 encryption using 2-SPGAL, with 2N2P-PCG integrated into the design, shows an average of 47.50% of energy saving compared to its CMOS counterpart, over the frequency range of 50 kHz to 250 kHz. The same 2-SPGAL based case study, with 2N-PCG integrated into the design, shows 51.18% of an average energy saving compared to its CMOS counterpart, over 50 kHz to 250 kHz. Further, the 2-SPGAL based PRESENT- 80 one round shows an average energy saving of 16.62% and 28.90% respectively for 2N2P-PCG and 2N-PCG integrated into the design compared to existing 2-phase adiabatic logic called 2- EE-SPFAL. We also subjected PRESENT-80 design of 2-SPGAL and CMOS against CPA attack. The 2-SPGAL, with 2N2P-PCG and 2N-PCG, integrated into one round of PRESENT-80 design protects the encryption key. However, the encryption key was successfully revealed in one round of PRESENT-80 design using CMOS logic. Therefore, the proposed 2-SPGAL logic can be useful to design energy-efficient and CPA resilient Implantable Medical Devices (IMDs). 

The adaptation of the Internet-of-Things (IoT) for consumer electronics has enabled us to uplift everyday life. Low-power smart and secure computing devices are needed to sustain the expected growth of consumer IoT. Adiabatic switching is a modern approach that recycles the energy stored in load capacitance to save energy. Further, the cryptographic circuit designed using adiabatic switching is secure against the Correlation Power Analysis (CPA) attack in contrast to the same circuit designed using standard CMOS. In this paper, we propose 2-SPGAL, a 2-phase sinusoidal signal based clocking implementation of Symmetric Pass Gate Adiabatic Logic (SPGAL). As a case study, we simulated the design of PRESENT-80 (a lightweight cryptographic scheme) one round with an in-built Power Clock Generator (PCG) with 45nm technology. The 2-SPGAL shows on an average 82.76% and 67.35% better energy saving compared to standard CMOS, and 2-EE-SPFAL (another 2-phase adiabatic logic), respectively at a frequency range from 100 kHz to 25 MHz with a load of 1 fF. The 2-SPGAL has 16.78% savings of the number of transistors compared to 2-EE-SPFAL for implementation of one round PRESENT-80. Further, the CPA attacks reveal the key in standard CMOS, however, 2-SPGAL PRESENT-80 adiabatic logic design was successful to protect the key. 

The objective of the article is to present an integrated True Random Number Generator (TRNG) and Physically Unclonable Function (PUF) architecture using Photovoltaic solar cells. We illustrate that the Photovoltaic (PV) solar cell sensor response can be engineered into dynamic (TRNG) and static responses (PUF). The proposed prototype uses the iterative Von Neumann post-processing scheme to produce random bits with 34% better throughput compared to a single Von Neumann operation. The random bit quality was checked by statistical test suites from the National Institute of Science and Technology (NIST) and achieves an average p-value of 0.45 at all variations in light intensity. The PUF response achieves 92.13% reliability and 50.91% uniformity. The integrated TRNG-PUF architecture is beneficial for resource-constrained Cyber-Physical System (CPS). 

Internet of Things (IoT) has facilitated the connection of many smart devices via internet. Recent cyberattacks have shown that resource constrained IoT nodes are easy prey that lead towards compromising the secrecy of the data and vulnerabilities could be exploited remotely to take control of safety-critical systems. Photoresistor sensors have applications in IoT systems, such as smart street lighting, intelligent cameras, light activated smart consumer electronics, smart home, smart healthcare, etc. Building hardware security primitives, such as True Random Number Generator (TRNG), based on the intrinsic properties of photoresistor would be a novel direction to develop cost-savvy IoT security primitives. Therefore, this paper proposes a TRNG prototype that is devised from uncertainty presents in photoresistor sensors. The proposed TRNG prototype does not require any complex interfacing for preprocessing the weak signal, thereby reducing the unnecessary delay and the recurring hardware cost. The proposed prototype employs the novel approach of additive scrambling that aids to sample sensors at a higher rate. The proposed TRNG has an average random bit generation rate of 8 kbps that is better than the recent work in the literature. The quality of randomness was validated by 15 test batteries of NIST STS test.