A new design and simulation of reversible gates in quantum-dot cellular automata technology

Power dissipation is the main limitation of all the nano electronics design techniques including Quantumdot Cellular Automata (QCA). The reversible computing is considered as the reliable solution to lower the power dissipation. In this paper, the contribution is divided into three parts. In the first part, a multi-objective synthesis method is presented for reversible functions (with the objective priority of gate counts (majority gates), gate levels, the number of NOT gates, and control inputs which are the input cells with fixed polarization used for programming 2-input OR and AND gates). Based on the proposed method, a new synthesis of many of well-known reversible gates is proposed. In the second part, a new method for converting irreversible functions to the reversible one in QCA technology is presented. This method has advantages such as: having of a minimum number of garbage outputs, converting of irreversible functions to reversible one directly and as optimal (So, in this method, a sub-optimal method of using of conventional reversible blocks such as Toffoli and Fredkin are not used), and so on. For showing the efficiency of the proposed method, it is applied to the 13 standard combinational functions. In the third part, new designs of QCA layouts are presented for gates synthesized in the previous section. Results show that our proposed method outperforms the best available methods in terms of area, complexity (cell amount), delay (clocking zones), and also in logic level in terms of levels, Control inputs, number of majority and NOT gates.