Carbon Nanotube FET Based High Performance Folded Cascode Op-Amp with Gain Enhancement-Performance Evaluation, Comparison and Optimization

This research paper focuses on the design and simulation of carbon nanotube based Folded Cascode Operational Amplifier (FC_OPAMP). The presented circuits are designed using pure Carbon Nanotube (CNT) and hybrid Carbon nanotube (CNT)-Complementary metal Oxide Semiconductor (CMOS) at 45 nm technology node, and performance parameters are compared with pure CMOS based design. It has been observed that CNT based designs show improved performance over CMOS based design. For pure CNT Field Effect Transistor (CNTFET) design, the DC gain is improved by 99.6%, Common mode rejection ratio (CMRR) is increased by 33.7%, slew rate is improved by 88.3% and the power dissipation is reduced by 10.5% as compared to CMOS based Op-Amp. Furthermore, an improvement of 34.6% and 115.2% is observed in phase margin and gain margin respectively of pure CNTFET based circuit which enhances the frequency stability of proposed circuit. The fundamental characteristics of the circuits are also evaluated by varying the Number of CNTs (N), inter-pitch of CNT (S) and the diameter of carbon nanotubes ( D CNT ) at 0.9 V supply voltage. It has been analyzed that optimizing the values of N, S and D CNT leads to improved circuit efficiency. Ultimately, low-pass and high-pass filters are implemented by presented CNT based FC_OPAMP.