Comparative Analysis of Various Adder Architectures on 28nm CMOS Technology

Since miniaturization of CMOS has taken place, speed and power are the most important parameters for any circuit, like speed of an adder is a critical parameter in the overall performance of an Arithmetic Logic Unit (ALU). In order to identify the best suitable 2-bit adder in terms of speed, power dissipation, area and leakage current acomparative study of five different kinds of standard 2-bit adder architectures, Ripple Carry (RCA), Carry Look ahead (CLA), Manchester Carry Chain (MCC), Carry Select (CSL) and Kogge Stone (KSA) adders has been done in this paper.The adders are re-designed, implemented and analyzed at supply voltages ranging from 0.6 - 1 V on 28nm CMOS Technology to improve the speed and power. Simulation results for the different adders show that MCC at 0.6V is 32.4% faster than RCA and 15.6% faster than CLA. RCA having minimum transistor count has the least power dissipation and CLA gives minimum leakage current for lower supply voltages, but as the supply voltage increases MCC produces the least leakage current.