A fast, numerical circuit-level model of carbon nanotube transistor

Recently proposed circuit-level models of carbon nanotube transistor (CNT) for SPICE-like simulators suffer from numerical complexities as they rely on numerical evaluation of integrals or internal Newton-Raphson iterations to find solutions of non-linear dependencies or both. Recently an approach has been proposed which eliminates the need for numerical integration when calculating the charge densities in CNT through the use of piece-wise linear approximation. This paper extends the effective employment of numerical piece-wise approximation to the solution of the Fermi-Dirac integral to accelerate the CNT model speed when evaluating the source-drain current while maintaining high modeling accuracy. Our results show a speed up of more than three orders of magnitude compared with the theoretical CNT model implemented in FETToy, used as a reference for verifying newer models. Comparisons of drainsource current characteristics of the new model against that in FETToy are presented, confirming that the accuracy of the proposed approach is maintained within less than 5% in terms of RMS error.