Quantum dot cellular automata is a popular nanotechnology which can overcome the limitations of CMOS technology due to its extremely small feature size and ultra low power consumption. In this paper we proposed the design of random number generator using Quantum dot cellular automata technology .In Quantum Dot Cellular Automata the basic elements are simple cells. The cells are used to construct majority voter gate, inverter and wire which are used to realize any complex function. In the given

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... esign, random number generator unit is constructed using a VHDL model of QCA elementary circuits which provides an approach to improve the complexity and system throughput of Random Number Generator. Index Terms-Quantum Dot Cellular Automata (QCA), Random Number Generator (RNG), VHDL, Majority voter Gate (MVG) I. INTRODUCTION Random number generators are key primitive for the variety of applications simulation, game playing, cryptography statistical sampling, evaluation etc. In many applications, it is desirable to optimize performance of the RNGs in terms of speed, area, and power dissipation, while producing high-quality random numbers. As the size of CMOS transistors keep shrinking, it will eventually hit its limitation. Hence, an alternative device has to be discovered to continually improve the development of electronics devices. Quantum-dot Cellular Automata (QCA) has been seen as a possible alternative to the current CMOS circuits. QCA devices show great promise to be faster and smaller than conventional microelectronic devices, and to operate at a fraction of the power. In this paper we proposes the design of RNG using QCA technology and will compare the different performance parameters with the RNG implemented using QCA technology. 1. QUANTUM DOT CELLULAR AUTOMATA (QCA) QCA was first proposed by Lent et.al in 1993 and as developed in 1997 [5]. It is expected that QCA plays an important role in nanotechnology research. QCA architecture is based on the coulombic interactions between many identical QCA cells. QCA technology consists of a group of cells which, when combined and arranged in a particular way, are able to perform computational functions. QCA technology transfers information by means of the polarization state of various cells in contrast to traditional computers, which use the flow of electrical current to transfer information. A QCA design provides advantages such as ultra-small factor, low power consumption and high speed clock circuits. QCA clock rate could be in the range of 1-2 THz[7]. A. QCA Cell : QCA is based on the interaction of bi-stable QCA cells constructed from four quantum-dots. A high-level diagram of two polarized QCA cells is shown in Fig. 1. Each cell is constructed from four quantum dots arranged in a square pattern. The cell is charged with two electrons, which are free to tunnel between adjacent dots. These electrons tend to occupy antipodal sites as a result of their mutual electrostatic repulsion. Thus, there exist two equivalent energetically minimal arrangements of the two electrons in the QCA cell as shown in Fig. 1(b). These two arrangements are denoted as cell polarization P = + 1 and P =-1 respectively. By using cell polarization P = +1 to represent logic "1" and P =-1 to represent logic "0" ,binary information can be encoded. (a)Structure of QCA cell