Quantum-dot Cellular Automata (QCA) has emerged as one of the alternative
technologies for current CMOS technology. It has the advantage of computing
at a faster speed, consuming lower power, and work at Nano- Scale. Besides
these advantages, QCA logic is limited to its primitive gates, majority
voter and inverter only, results in limitation of cost-efficient logic
circuit realization. Numerous designs have been proposed to realize various
intricate logic gates in QCA at the penalty of non-uniform clocking and
improper layout. This paper proposes a Composite Gate (CG) in QCA, which
realizes all the essential digital logic gates such as AND, NAND, Inverter,
OR, NOR, and exclusive gates like XOR and XNOR. Reportedly, the proposed
design is the first of its kind to generate all basic logic in a single
unit. The most striking feature of this work is the augmentation of the
underlying clocking circuit with the logic block, making it a more realistic
circuit. The Reliable, Efficient, and Scalable (RES) underlying regular
clocking scheme is utilized to enhance the proposed design?s scalability and
efficiency. The relevance of the proposed design is best cited with coplanar
implementation of 2-input symmetric functions, achieving 33% gain in gate
count and without any garbage output. The evaluation and analysis of
dissipated energy for both the design have been carried out. The end product
is verified using the QCADesigner2.0.3 simulator, and QCAPro is employed for
the study of power dissipation.