Design of a Compact Reversible Carry Look-Ahead Adder Using Dynamic Programming

This paper presents a new method for designing a reversible carry look-ahead adder (RCLA) based on dynamic programming. In this method, we propose a faster technique for generating carry output, which also outperforms the existing ones in terms of number of operations. In addition, we design a compact reversible carry look-ahead circuit based on the proposed technique. In order to optimize our design, we propose a first ever known Reversible Partial Adder (RPA) circuit with the optimum numbers of the quantum cost and garbage outputs which concurrently produce carry propagation signal, carry generation signal and summation of the inputs. Using RPA as a unit element of RCLA construction, we optimize the designs of RCLA and show that the proposed design is better than the existing ones in terms of the number of gates, quantum cost, garbage outputs and delay with the help of Microwind DSCH 3.5, e.g., the proposed 128-bit adder improves 77.55% on number of gates, 10% on garbage outputs, 2.16% on delay and 77.61% on quantum cost over the existing best one.