A novel three-input approximate XOR gate design based on quantum-dot cellular automata

Quantum-dot cellular automata (QCA) are one of the most promising emerging nanoelectronic paradigms used for designing computers and very large-scale integration circuits. Many applications can tolerate the errors and imprecision of digital systems; thus, approximate computing is widely used in such cases. Exclusive OR (XOR) gates are among the major gates, based on which other gates could be developed. A three-input XOR gate is considered to be a basic gate in designing compressors as one of the most important parts of the arithmetic logic unit. Several studies have focused on the accuracy of XOR gate in the QCA technology. However, using approximation in designing XOR gates remains a significant concern in this regard. To the best of our knowledge, the present study is the first to introduce a novel three-input approximate XOR gate. This gate is utilized in designing approximate 4-2 compressors for reducing circuit complexity, which can be achieved by the minimum number of the gates and area-efficient designs.