Novel Subtractor Design Based on Quantum-Dot Cellular Automata (QCA) Nanotechnology

Quantum-dot cellular automaton (QCA) is a novel nanotechnology with a very different computational method in compared with CMOS, whereas placement of electrons in cells indicates digital information. This nanotechnology with specifications such as fast speed, high parallel processing, small area, low power consumption and higher switching frequency becomes a promising candidate for CMOS technology. In this paper, a new architecture of Half and Full subtractor based on the QCA is proposed. We take advantage of optimal XOR gate in designing these arithmetic units, which has been already designed based on the QCA majority voter gate. Using this XOR gate in the architecture of designed arithmetic units in this paper, reduces number of used QCA cells to 55 and 136 for Half and Full subtractor, respectively. Proposed design is more efficient in terms of cell counts, covered area and delay, than the conventional subtractors based on the QCA. These subtractors are designed and simulated using QCA Designer 2.0.3.