A Robust Design of Coplanar Full adder and 4-bit Ripple Carry Adder using Qunatum-dot Cellular Automata

Emerging technology like Quantum-dot Cellular are prominent candidate for replacing present CMOS based technology. Continuous increase in limitations faced by present CMOS based devices like heat and power dissipation, scaling problems and performance degradation are few reasons for this replacement. This paper explains another way of designing a 1-bit full adder and 4-bit Ripple Carry Adder (hereafter referred as RCA). A coplanar crossover approach in QCA is used for designing the above adder. Designing a full adder using coplanar approach leads to increase in area size but it develops the whole circuit on single layer, which makes physical realization and fabrication of this circuit very simple. For Coplanar full adder, 95 cells occupying 0.12 mu m(2) area and for 4-bit RCA 366 cells covers 0.50 mu m(2) area are obtained. QCA Designer tool is used for designing, evaluation and testing of our design. Simulation result shows a very robust design of our coplanar adder.