Quantum-dot cellular automata (QCA), a nano-scale computer framework, is developing as a potential alternative to current transistor-based technologies. However, it is susceptible to a variety of fabrication-related errors and process variances because it is a novel technology. As a result, QCA-based circuits pose reliability-related problems since they are prone to faults. To address the dependability challenges, it is becoming increasingly necessary to create fault-tolerance QCA-based circuits. On the other hand, the applications of code converters in digital systems are essential for rapid signal processing. Using fault-tolerance XOR and multiplexer, this research suggests a nano-based binary-to-gray and gray-to-binary code converter circuit in a single layer to increase efficiency and reduce complexity. The fault-tolerance performance of the suggested circuits against cell omission, misalignment, displacement, and extra cell deposition faults has significantly improved. Concerning the generalized design metrics of QCA circuits, the fault-tolerance designs have been contrasted with the existing structures. The proposed fault-tolerance circuits' energy dissipation findings have been calculated using the precise QCADesigner-E power estimator tool. Using the QCADesigner-E program, the proposed circuits' functionality has been confirmed. The results implied the high efficiency and applicability of the proposed designs.
This paper introduces a novel ultra-broadband Metamaterial Absorber (UBMA) demonstrating significant absorption capabilities across a wide terahertz frequency range from 2.42 THz to 6.11 THz. The 3.7 THz bandwidth represents 87% of the central frequency. The proposed UBMA comprises three layers: a star-shaped metal patch on top, a dielectric substrate in the middle, and a metallic ground plane below. Simulations using CST Microwave Studio software reveal that the design achieves high absorption at five distinct frequencies: 2.47, 3.45, 4.89, 6.01, and 6.87 THz, with absorption rates of 99% for the first four peaks and 90% for the fifth peak. The study of electric field and surface current distribution provides insights into the absorption mechanism. While the UBMA exhibits polarization-independent performance, its angular response shows some sensitivity to the incident angle, especially beyond 30° Despite this, the absorber maintains over 70% absorptivity up to a 45° incidence angle for both TE and TM polarizations within specific frequency ranges. The simple structure combined with high absorption efficiency makes the UBMA suitable for THz imaging, detection, and stealth applications, although its angular sensitivity must be considered for certain applications.

