Adder Designs and Analyses for Quantum-Dot Cellular Automata

Quantum-dot cellular automata (QCA) is an emerging nanotechnology for electronic circuits. Its advantages such as faster speed, smaller size, and lower power consumption are very attractive. The fundamental device, a quantum-dot cell, can be used to make gates, wires, and memories. As such it is the basic building block of nanotechnology circuits. While the physical nature of the nanoscale materials is complicated, the circuit designer can concentrate on the logical and structural design, so the design effort is reduced. Because of its novelty, the current literature shows only simple circuit structures. So this paper broadens the QCA circuit designs with larger circuits and shows analyses based on those designs. This paper proposes three kinds of adder designs in QCA. Ripple carry adders, carry lookahead adders, and conditional sum adders are designed and simulated with several different operand sizes. The designs are compared according to complexity, area, and delay