Summary
Quantum‐dot cellular automata (QCA) is a transistor‐free technique for designing digital circuits. It is a substitute for CMOS technology for producing low‐energy and high‐speed digital circuits. In addition, the digital comparator is an important digital circuit; its fault‐tolerant design is examined in this article. Additionally, a coplanar QCA‐based fault‐tolerant comparator circuit with a small number of cells is suggested. The QCADesigner is used to achieve exact simulation results. The suggested fault‐tolerant comparator requires 63 QCA cells, uses 0.8 normalμ$$ \upmu $$m2, and has three clock cycles delay in accomplishing its purpose. Furthermore, simulation results demonstrate that the suggested comparator design with a limited number of cells can achieve a fault‐tolerant of 80% against cell missing, extra cell, cell displacement, and cell rotation faults.
Tunable multifunctional metasurface has wide application such as optical electromagnetics and material science. In this paper, a terahertz (THz) metasurface based on double graphene split-ring resonators (GSRRs) are theoretically demonstrated, integrating dual-band absorption and plasmon-induced
transparency (PIT) filtering effect. The structure is composed of a monolayer of graphene arrays with periodic patterns and a metal ground surface partitioned by a silicon dioxide dielectric layer. When the initial structure of unit cell is three-layer sandwich structure (bottom metal plate),
its dual-frequency absorption spectra appears two peaks at 2.50 THZ and 3.38 THz, which are 99.98% and 97.94%, respectively. Then the mechanism of double band absorption is explained by analyzing the distribution of surface current and electric intensity of the absorbent material. When the
initial arrangement of the cell is a double layer structure (without the bottom metal plate), the PIT effect will occur when the incident wave is y-polarized. And in a certain range to achieve more than 90% of the transmission. In addition, CST simulations demonstrate that the designed model
supports changing the operating frequency by adjusting the Fermi energy of graphene The dual-function terahertz metasurface proposed in this work has broad application prospects in broadband communication, terahertz imaging and industrial sensors.
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