Vhdl-ams Implementation of a Numerical Ballistic Cnt Model

This contribution presents a VHDL-AMS implementation of a novel numerical carbon nanotube transistor (CNT) modelling approach which relies on a flexible and efficient cubic spline non-linear approximation of the non-equilibrium mobile charge density. The underlying algorithm creates a rapid and accurate solution of the numerical relationship between the charge density and the self-consistent voltage. This leads to a speed-up in the calculation of the current through the channel by about two orders of magnitude without losing much accuracy. The numerical approximation is accurate within less than 1.5% of the normalised RMS error compared with a previously reported theoretical modelling approach. The proposed VHDL-AMS implementation has been used in simulations of a logic inverter in SystemVision to demonstrate the feasibility of applying the spline-based technique in development of efficient and accurate CNT models for applications in circuit-level simulators.