Novel high-performance QCA Fredkin gate and designing scalable QCA binary to gray and vice versa

In the design of digital logic circuits, QCA technology is an excellent alternative to CMOS technology. Its advantages over CMOS include low power consumption, fast circuit switching, and nanoscale design. Circuits that convert data between different formats are code converters. Code converters have an essential role in high-performance computing and signal processing. In this paper, first, we proposed a novel QCA structure for the quantum reversible Fredkin gate. Second, we proposed 4-bit and 8-bit QCA binary-to-gray converter and vice versa. For the second proposal, both reversible and irreversible structures are suggested. The proposed structures are scalable up to N bits. To change the conversion type from B2G to G2B, we use a 2:1 QCA multiplexer. The proposed QCA Fredkin is applied in the reversible design of QCA code converters as multiplexers. The suggested designs are simulated using the QCADesigner tool. Then we calculated figures of merit, including cell counts, occupied areas, and clock zones. Finally, we compare the proposed structures to existing research. Our proposed approach is the first quantum-dot cellular automata design to perform B2G conversion and G2B in a single QCA circuit. The proposed designs are scalable. Specifications are reported.