The digital designer´s complete lossy transmission line model

Presents a technique for simulation of the lossy behavior of transmission line elements that addresses the most common problems that digital designers encounter when called upon to simulate links operating above 500 Mb/sec. Models that seek to represent the distributed losses of the transmission lines with a multiple section RLC network run into complexity related problems when the number of sections exceeds about 100. The SPICE integration routine begins to insert its own oscillations and may fail to converge, yielding no answer or at best a loss of time when the user tries various methods to achieve convergence. In addition, the time to evaluate the SPICE model can become an annoyance or a real time sink for the designer. Alternative methods using S-parameters or Laplace transforms are often compute intensive as well. The model presented addresses the above problems by reducing the number of elements to a minimum with innovative circuit design, and by using appropriate approximations. It can be implemented in any SPICE version, and it works unchanged in both AC and transient modes.