European Journal of Scientific Research ISSN 1450-216X Vol.48 No.3 (2011), pp.516-526 © EuroJournals Publishing, Inc. 2011 http://www.eurojournals.com/ejsr.htm Logic Circuit Design in Nano-Scale using Quantum-Dot Cellular Automata Mehdi Askari Engineering Department, Behbahan Higher Educational Complex, Behbahan, Iran E-mail: Mehdiaskari58@yahoo.com Maryam Taghizadeh Islamic Azad University of Behbahan, Behbahan, Iran Abstract One of the emerging technologies that being investigated as an alternative to CMOS VLSI is Quantum-Dot Cellular Automata (QCA). Its advantages such as faster speed, smaller size, and lower energy consumption are very good-looking. Unlike conventional digital circuits in which information is transferred using electrical current, QCA transfers information by propagate a polarization state. This paper proposes a detailed design analysis of combinational and sequential logic circuits for quantum-dot cellular automata. The aim is to maximize the circuit density and focus on a layout that is minimal in its use of cells. Keywords: Quantum-dot cellular automata, Logic circuit, Nanoelectronic circuit, QCA 1. Introduction Fundamental physical limitation of CMOS technologies, make extensive research in recent years in nanotechnology for future generation IC. Gordon Moore has predicted, in 1965, that the capacity of a computer chip would grow exponentially with time. Since then, the so-called Moore’s Law had governed the development and performance of microprocessors [1, 2]. Shrinking transistors has been the major trend to achieve circuits with fast speed, high densities and low power dissipation. However, when scaling comes down to submicron level, many problems occur. Physical limits like quantum effects and non-deterministic behavior of small currents and technological limits such as high power consumption and design complexity may hold back the further progress of microelectronics using conventional circuit scaling [1, 3]. Thus, to continue trends of increasing microprocessor performance, other technologies should be studied. As an attractive alternative to CMOS-VLSI, researchers have proposed an approach to computing with quantum dots, the quantum cellular automata (QCA). It was proposed by Lent et al. in 1993 [4]. QCA is based upon the encoding of binary information in the charge configuration within quantum dot cells. Computational power is provided by the Coulombic interaction between QCA cells. No current flows between cells and no power or information is delivered to individual internal cells [4]. The local interconnections between cells are provided by the physics of cell-to-cell interaction due to the rearrangement of electron positions [2, 5]. Recent papers show that QCA can achieve high density, fast switching speed, and room temperature operation [6].