In recent years, reversible computing and reversible logic has rapidly emerged as one of the promising technologies for designing low-power circuits. It has applications in nanotechnology, quantum computing, quantum dot cellular automata (QCA), DNA computing, optical computing and even in CMOS low-power designs. In this work, we propose basic circuits of reversible sequential logic which are the building blocks of a sequential CPU. First, a novel design of a reversible D-flip flop is proposed which is two times faster than the conventional D flip- flop as well as its reversible counterparts. Further new designs of a sequential shift register, reversible adder and multiplier is proposed. These circuits can be used for constructing a reversible CPU which has sequential elements. Practical implementation of the proposed designs can be achieved with the existing technologies in CMOS and nanotechnology.

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