A Novel Reversible BCD Adder For Nanotechnology Based Systems

This paper proposes two reversible logic gates, HNFG and HNG. The first gate HNFG can be used as two Feynman Gates. It is suitable for a single copy of two bits with no garbage outputs. It can be used as “Copying Circuit” to increase fan-out because fan-out is not allowed in reversible circuits. The second gate HNG can implement all Boolean functions. It also can be used to design optimized adder architectures. This paper also proposes a novel reversible full adder. One of the prominent functionalities of the proposed HNG gate is that it can work singly as a reversible full adder unit. The proposed reversible full adder contains only one gate. We show that its hardware complexity is less than the existing reversible full adders. The proposed full adder is then applied to the design of a reversible 4-bit parallel adder. A reversible Binary Coded Decimal (BCD) adder circuit is also proposed. The proposed circuit can add two 4-bit binary variables and it transforms the result into the appropriate BCD number using efficient error correction modules. We show that the proposed reversible BCD adder has lower hardware complexity and it is much better and optimized in terms of number of reversible gates and garbage outputs with compared to the existing counterparts.