This document discusses the design and implementation of combinational circuits using reversible gates to reduce power consumption. It describes various reversible gates like NOT, Feynman, Toffoli, and Fredkin gates. Reversible decoders are designed using these gates to implement 2x4, 3x8, and 4x16 decoders with lower quantum costs and garbage outputs compared to traditional designs. The reversible decoder approach allows designing combinational circuits like adders and comparators with better performance. Simulation results demonstrate the working of the designed reversible decoders.