Realization and Optimization of CNFET Based Operational Amplifier at 32-nm Technology Node A. Kumar, S. Prasad, A. Islam Dept. of Electronics and Communication Engineering Birla Institute of Technology (Deemed University) Mesra, Ranchi, Jharkhand, India kumar.amresh.singh@gmail.com , s.prashad@bitmesra.ac.in aminulislam@bitmesra.ac.in Abstract— Carbon nanotube field effect transistor (CNFET) is a new emerging device which will extend Moore’s law beyond 22-nm technology node. In the future, CNFET is the most potential candidate to replace CMOS due to its better electrostatics and higher mobility. Improved intrinsic CV/I gate delay and scalability adds to the preference of CNFET over MOSFET. This paper presents a comparative study of CMOS version and CNFET version of Operational amplifier at 32-nm technology nodes. The performance of CNFET based amplifier has been thoroughly investigated in terms of its input resistance, output resistance and AC gain. This study shows that there is considerable improvement in the above feature of amplifier using CNFET. It is founded that CNFET based amplifier have 9 times AC gain, 100 times input résistance and output resistance decrease by 9 times compared to MOSFET based amplifier at 32-nm technology node. Furthermore, comparison between two technologies for same gain bandwidth product (GBP) has also been presented. Keywords— CNFET; CNT; OPAMP; nanoelectronics I. INTRODUCTION From past four decades, device engineers have concentrated on the scaling and performance of device but as per International Technology Road map for Semiconductors (ITRS) [1] suggestion by 2015 gate length of MOSFET will be 10 nm which means that CMOS technology will face significant challenges due to the high channel doping required, band tunneling across the junction and gate induced drain leakage (GIDL), high field effect, lithographic limits and quantum confinement effect. Carbon nanotube field effect transistor (CNFET) is one of the most promising devices due to its ballistic transport capability, narrow diameter of the order of few nm, superior electrostatic and structural properties[2]-[3]. In CNFET, as carbon nanotube (CNT) is the only path present surrounded by a SiO 2 , it offers better control of gate voltage. Furthermore, the use of high–k dielectric could reduce the short channel effect by increased capacitive coupling [4]. This paper realizes a two-stage operational amplifier using CNFET and compares its design metrics with its CMOS counterpart. The investigation shows that the CNFET realization of op amp exhibits higher overall efficiency due to ultralong (~1 μm) mean free path for elastic scattering [5]-[7]. This remainder of this paper is organized as follows. The basic characteristics of CNFET structure is introduced in Section II. Section III presents an overview of op amp design using CNFET. The design and performance analysis of the CNFET-based op amp is presented in Section IV. Section V concludes the paper. II. CARBON NANOTUBE FIELD EFFECT TRANSISTOR The past few years witnessed a dramatic increase in nanotechnology research, especially in the nanoelectronics field. Among the nanoelectronic devices investigated till date, CNFET seems to have the brightest prospect as per its better electronic characteristics. Speed enhancement due to scaling down to 16-nm and 10-nm technology node has given the impetus to its use. Leakage current, high field effect, short channel effect and lithographic limit problems associated MOSFET are largely taken care of in CNFET [8]. Also fabrication related issues of CNFET have been solved and hence CNFET-based circuit will surely dominate in the industry in future [9]-[10]. In CNFET channel are made from a single CNT or a bunch of CNT in place of bulk silicon structure present in traditional MOSFET. CNT is basically a long, thin allotropic carbon tube which provides a single path between source and drain. CNTs are sheets of graphite rolled into hollow cylinders of diameters varying from 0.4 nm to 4 nm. Depending on the direction in which they are rolled (called chirality) a CNT can be semiconducting with distinct band gap or it can be metallic with no bandgap. The resulting structure is called single-walled carbon nanotube (SWCNT). If several SWCNTs with varying diameter are rolled concentrically inside one another, then the resulting structure is called multi-walled carbon nanotube (MWCNT), diameter ranging from several nm to tens of nm [11]. An SWCNT can work as semiconducting or metallic depending on its chirality (n 1 , n 2 ) − the direction in which it is rolled up. The CNT acts as metal if n 1 = n 2 or n 1 – n 2 = 3i, where i is an integer. Otherwise, CNT works as semiconductor.