Modeling of nonlinear active regions in TLM (distributed circuits)

A transmission line matrix (TLM) method for modeling distributed circuits containing nonlinear active elements and structures is demonstrated. The scattering properties of the nonlinear element are expressed in terms of differential equations that are solved by stepwise integration with the time step of the TLM algorithm. A cavity oscillator with an active diode with a finite cutoff frequency has been modeled. Spurious oscillations of the TLM mesh that regularly occur when including negative conductivity or pulse reflection coefficients larger than unity were effectively suppressed.>