Design of reversible sequential elements with feasibility of transistor implementation

This paper presents the novel designs of reversible sequential circuits (latches and flip flops). The proposed reversible latches and flip flops are designed from reversible Fredkin, Feynman and Toffoli Gates. Two new reversible gates called modified Fredkin gate (MFG) and Modified Toffoli Gate (MTG) are also proposed to design the optimized implementations. The proposed designs are better than the recently proposed ones in terms of number of reversible gates and garbage outputs. In order to reach towards the goal of transistor implementations of proposed reversible sequential circuits, transistor implementation of the existing Feynman gate, Fredkin gate, Toffoli gates as well as the proposed MTG and MFG are also proposed. The proposed transistor implementations are completely reversible in nature, i.e., suitable for both the forward and backward computation.