Binary number system based digital logic design has been in use for long with phenomenal increase in circuit sizes, working with binary logic system is becoming increasingly difficult. Multi-valued logic system reduces the significant amount of design effort. Multi-valued ternary logic under GF (3) and quaternary logic under GF (4) are available in the literature, but circuit design based on these logic systems is very few. As traditional computing devices based on irreversible logic are approaching their limit in terms of heat dissipation, power and speed requirement. Reversible computing is emerging as an alternative technology. Usage of multi-valued logic for irreversible computing is also growing. Ternary and quaternary logic based reversible gate have been proposed recently. Ternary logic based design has further been enhanced using balanced logic levels. But, the same is not available for quaternary logic. In this paper, we propose balanced quaternary logic and synthesis approach, which offers significant advantages in logic design. Small circuits like adder subtractor have also been designed based on that approach. We feel that balanced logic based approach will open a new era in multivalued logic design.
Reversible computing offers a possible solution for high performance computing and low power consumption. For hardware implementation of reversible logic, optical computers are emerging as one of the promising alternative. Recently, in the literature, reversible logic gates and combinational circuits have been proposed in optical domain using Semiconductor Optical Amplifier (SOA) based Mach Zehnder interferometer (MZI) switches due to its significant advantages such as high speed, low power, fast switching and ease of fabrication. Optical reversible designs have used ad-hoc approaches and require high cost in terms of MZI switches, Beam Splitters (BS), and Beam Combiners (BC) as well as optical delay. In this work, an optical reversible MNOT gate and all-optical realization of 4×4 Toffoli Gate have been proposed which is used in all-optical realization of optimized reversible combinational circuits. A general design approach to realize all-optical reversible circuits based on MZI switches has been proposed first time in the literature. Optimized all-optical reversible 2×1 multiplexer and full adder circuits have been designed using these proposed gates and design approach. All-optical reversible designs of 4×1 multiplexer, 1×4 Demultiplexer and 3to8 Decoder circuits have also been presented in this work first time in the literature. Our results have shown significant improvements over existing designs in terms of MZI switches, BS, BC and optical delay.
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