Best implementations of quaternary adders

The implementation of a quaternary 1-digit adder composed of a 2-bit binary adder, quaternary to binary decoders and binary to quaternary encoders is compared with several recent implementations of quaternary adders. This simple implementation outperforms all other implementations using only one power supply. It is equivalent to the best other implementation using three power supplies. The best quaternary adder using a 2-bit binary adder, the interface circuits between quaternary and binary levels are just overhead compared to the binary adder. This result shows that the quaternary approach for adders use more transistors, more chip area and more power dissipation than the corresponding binary ones.