  Quantum-dot Cellular Automata (QCA) as a nanoscale transistor-less device
technology offers distinguishing advantages over the limitations of CMOS
circuits. While more than 2 decades of design progress have been achieved with
QCA, a comprehensive composition approach for the layout design in this
technology is needed. In this study, the Priority-Phased Decomposition-Driven
(PPDD) QCA logic design methodology is proposed. In this methodology, after
partitioning combinational and sequential circuits into primary-level priority
blocks including 2:1 MUX and XOR gates, and secondary-level priority blocks
comprising multi-input majority gates, there are three streamlined approaches
which are developed to compose the desired QCA circuit using blocks from each
priority level.
