Pade approximation applied to lossy transmission line circuit simulation

An approach for transient simulation of lossy transmission lines terminated in arbitrary nonlinear elements based on convolution simulation is introduced. By making use of the Pade approximations of each line´s characteristic admittance function and exponential propagation function, it is possible to derive a recursive convolution formulation, which greatly reduces the amount of computation needed to perform convolutions. The approach can handle frequency-varying effects, such as skin effects. The approach is incorporated into the stepwise equivalent conductance timing simulator, SWEC; therefore, no Newton-Raphson iteration is needed to simulate lossy lines with nonlinear terminals. Comparisons with SPICE3.e indicate that SWEC, which gives accurate results, can be one to two orders of magnitude faster