A Novel Design for Quantum-dot Cellular Automata Cells and Full Adders

Quantum dot Cellular Automata (QCA) is a novel and potentially attractive technology for implementing computing architectures at the nano-scale. The basic Boolean primitive in QCA is the majority gate. In this paper we present a novel design for QCA cells and another possible and unconventional scheme for majority gates. By applying these items, the hardware requirements for a QCA design can be reduced and circuits can be simpler in level and gate counts. As an example, a 1-bit QCA adder is constructed by applying our new scheme and is compared to the other existing implementation. Beside, some Boolean functions are expressed as examples and it has been shown, how our reduction method by using new proposed item, decreases gate counts and levels in comparison to the other previous methods. I. Introduction Quantum Cellular Automata (QCA) is a nanotech-nology that has recently been recognized as one of the top six emerging technologies with potential applications in future computers [1][2]. It has gained significant popularity in recent years. This is mainly due to rising interest in creating computing devices and implementing any logical function with that. The basic building block of QCA circuit is majority gate; hence, efficiently constructing QCA circuits using majority gates has attracted a lot of attentions [3]. Several studies have reported that QCA can be used to design general purpose computational and memory circuits [4]. QCA is expected to achieve high device density, very high clock frequency and extremely low power consumption [2]. In recent years the development of integrated circuits has been essentially based on scaling down that is, increasing the element density on the wafer. Scaling down of complementary metal oxide semiconductor CMOS circuits, however, has its limits. Above a certain element density various physical phenomena, including quantum effects, conspire to make transistor operation difficult if not impossible. If a new technology is to be created for devices of nanometer scale, new design principles are necessary. One promising approach is to move to a transistorless cellular architecture based on interacting quantum dots, quantum dot cellular autom-ata QCA [5][14].