Efficient Design of a Hybrid Adder in Quantum-Dot Cellular Automata

This paper first presents an efficient quantum-dot cellular automata (QCA) design for the Ladner-Fischer prefix adder. We then present an efficient QCA design of a hybrid adder that combines the Ladner-Fischer adder with a ripple carry adder. We show that the hybrid adder has better performance (in terms of latency) in QCA than a Ladner-Fischer or a ripple carry adder. We also show that the hybrid adder has a smaller area-delay product than existing adder designs in QCA. Results of simulation in QCADesigner are also given and they support the theory presented.