Robust passivity enforcement of frequency dependent transmission line models

Passivity must be enforced on rational macromodels in order to ensure a stable time domain simulation. This paper investigates procedures for enforcing passivity for transmission line models based on the method of characteristics. Adding a conductive correction term externally to the line terminals is shown to be a robust and simple procedure for ensuring a passive model. The perturbation of the line model behavior is reduced by shaping the correction term using a low order rational function.