CNTFET-based design of multi-bit adder circuits

This paper presents a novel design of a high performance full adder cell based on carbon nanotube field-effect transistors (CNTFET). This full adder cell has been designed to be used in ripple carry adder (RCA) optimally so that carry-propagation delay decreases without increase in hardware costs. High speed in RCA structure, the low number of transistors and simplicity in design are the main advantages of the proposed design in comparison with the previous works. Moreover, to increase the proposed RCA speed, carry-propagation chain has been reduced to six cells using only 14 transistors per 4 bits in the worst case, regardless of the adder width. The simulation results using HSPICE demonstrate that a significant improvement in delay, power and power-delay product compared with the state-of-the-art works can be achieved. The results in different temperatures, supply voltages, frequencies and load capacitors have also been obtained.