I.J. Modern Education and Computer Science, 2015, 3, 19-25 Published Online March 2015 in MECS (http://www.mecs-press.org/) DOI: 10.5815/ijmecs.2015.03.03 Copyright © 2015 MECS I.J. Modern Education and Computer Science, 2015, 3, 19-25 A Novel Quaternary Full Adder Cell Based on Nanotechnology Fazel Sharifi Department of Electrical and Computer Engineering, Shahid Beheshti University, Tehran, Iran Email: f_sharifi@sbu.ac.ir Mohammad Hossein Moaiyeri Department of Electrical and Computer Engineering, Shahid Beheshti University, Tehran, Iran Email: h_moaiyeri@sbu.ac.ir Keivan Navi Department of Electrical and Computer Engineering, Shahid Beheshti University, Tehran, Iran Email: navi@sbu.ac.ir Abstract—Binary logic circuits are limited by the requirement of interconnections. A feasible solution is to transmit more information over a signal line and utilizing multiple-valued logic (MVL). This paper presents a novel high performance quaternary full adder cell based on carbon nanotube field effect transistor (CNTFET). The proposed Quaternary full adder is designed in multiple valued voltage mode. CNTFET is a promising candidate for replacing MOSFET with some useful properties, such as the capability of having the desired threshold voltage by regulating the diameters of the nanotubes, which make them very appropriate for voltage mode multiple threshold circuits design. The proposed circuit is examined, using Synopsys HSPICE with the standard 32 nm CNTFET technology with different temperatures and supply voltages. Index Terms—Carbon nanotube FET (CNTFET), Quaternary logic, Full Adder, Multiple-Vth design, Nanoelectronics. I. INTRODUCTION Traditional computer systems use binary logic for their operations. However, Multiple-valued logic (MVL) circuits have been designed over the last decades as an alternative to binary circuits. The main advantage of the MVL is reduction in the number of interconnections, which is a serious problem in binary integrated circuits of the present time. Multiple-valued logic seeks to improve the information processing efficiency of a circuit by transmitting more information on each signal line than the simple binary logic and by implementing complex functions of the inputs in a single gate. However, MVL using has been restricted due to the fact that compact and stable MVL circuits are hard to be designed, the noise margins on multiple valued lines are reduced and most importantly there is a need to perform conversions to and from the binary world. Accordingly, designers using the MVL paradigm have mostly focused on the ternary (i.e. radix 3) and the quaternary (i.e. radix-4) number systems. Ternary system consists of three digits, namely {0, 1, 2} and quaternary system consists of four digits {0, 1, 2, 3}. However, quaternary logic seems to be more interesting due to the simple conversion between quaternary signals and binary signals. On the other hand, scaling down the feature size of the metal-oxide semiconductor (MOS) technology deeper in nano-ranges leads to numerous critical challenges and problems, which will considerably reduce its suitability for energy efficient applications in the time to come. To overcome these problems, such as short channel effects, reduced gate control and high leakage power dissipation, researchers are working towards new technologies. These technologies, such as single electron transistor, quantum dot cellular automata and carbon nanotube field effect transistor (CNTFET) are being studied to replace the customary silicon based CMOS technology in the near future [1]-[3]. Among these emerging nanotechnologies, CNTFET seems to be more appropriate on account of its likeness with MOSFET in terms of inherent electrical properties which makes it possible to utilize previously designed CMOS structures in the CNTFET technology without any significant modifications. Moreover, the unique one-dimensional band structure of the CNTFET represses backscattering and causes near-ballistic operation, which results in very high-speed operation [4]. One of the important properties of CNTFETs which is very useful for transistor sizing of complex circuits is the same mobility for N-FET and P-FET and consequently same current drive capability. Generally CNTFETs are faster than MOSFETs and also consume less power. MVL circuits can be designed either in current mode or voltage mode. CMOS voltage mode MVL circuits are based on multiple-threshold design which can be achieved by applying different bias voltages to the bulk terminal of transistors. This method is not efficient and leads to very complex and high-cost fabrication. In a