Designing of a dual-functional XOR block in QCA technology

Abstract

Quantum-dot cellular automata (QCA) technology was proposed as a way to implement digital circuits with a transistorless approach for overcoming CMOS limitations in terms of short channel effects and scale-down continuity. The main building block in QCA technology is the square cell with a couple of free movement electrons, the electrons’ configuration inside the cell gives the cell the ability to represent binary information. Researchers were attracted to QCA because of its impressive features such as size and speed. Many important circuits, such as multiplexers and exclusive-OR, were presented in QCA technology with various layouts, looking for reducing the main metrics such as cell count, area, and implementation cost. In this work, a dual functional XOR block is proposed. The proposed block can function as a 2-input XOR or a 3-input XOR, providing greater flexibility. When compared to earlier 3-input XOR gates that did not have the dual function, the results show a significant improvement in cell count, area, and cost of about 7%, 50%, and 54%, respectively. The QCADesigner software is used to design the block as well as for verification issues.

Keywords

• qca technology
• qca-xor
• qcadesigner
• nanotechnology
• nanocircuits