Low Power and Optimized Ripple Carry Adder and Carry Select Adder Using MOD-GDI Technique

Abstract

Adders are the most important fundamental blocks of the digital systems which are used in a wide variety of applications. Among them the first basic adder is the Ripple Carry Adder (RCA) and the fastest adder is the Carry Select Adder (CSA). Though all these adders are existed, the speed adding using low power and optimized area is still a challenging issue. In this paper a new technique, Modified Gate Diffusion Input (MOD-GDI) is used to achieve an optimized design with less transistor count and low power dissipation. In the proposed work the 8-bit, 16-bit Ripple Carry Adder and the 8-bit, 16-bit Carry Select Adder have been designed using the CMOS and MOD-GDI techniques. The comparison of their power dissipations and overall transistor count is done and proved that low power and optimized designs are achieved through MOD-GDI technique. The simulation is carried out using Mentor Graphics tool with a supply voltage of 1.8 V at 90 nm technology.