Design of High Performance Quaternary Adders

Design of the binary logic circuits is limited by the requirement of the interconnections. A possible solution could be arrived at by using a larger set of signals over the same chip area. Multiple-valued logic (MVL) designs are gaining importance from that perspective. This paper presents two types of multiple-valued full adder circuits, implemented in Multiple-Valued voltage-Mode Logic (MV-VML). First type is designed using one hot encoding and barrel shifter. Second full adder circuit is designed by converting the quaternary logic in to unique code, which enables to implement circuit with reduced hard ware. Sum and carry are processed in two separate blocks, controlled by code generator unit. The design is targeted for the 0.18 µm CMOS technology and verification of the design is done through Synopsis HSPICE and COSMOSCOPE Tools. Area of the designed circuits is less than the corresponding binary circuits and quaternary adders because number of transistors used are less.