Nowadays Quantum-dot Cellular Automata (QCA) is one of the new technologies in nanoscale which can be used in future circuits. Most digital circuits are implemented with CMOS technology, but CMOS has some problems like power consumption and circuit size. So, for solving these problems a new method (QCA) is presented. It is clear that converters play a crucial role in the digital world. So, due to the aforementioned point, in this paper, two digital code converters, containing an excess-3 to decimal, and a decimal to excess-3 code converter are presented. The tile method is used to design proposed circuits in quantum-dot cellular automata (QCA) nanotechnology. The tile method gives a unique block for the majority and NOT gates. This property facilitates integration. Both of the proposed code converters have 1.75 clock cycles delay and have an energy dissipation of about 100meV. In the excess-3 code to decimal converter, 516 cells are used, which occupy an area equal to 0.43µm2 also in the decimal to excess-3 code converter. 321 cells are used, which occupy an area equal to 0.28 µm2.
