Adaptation of “SPICE3” to simulation of lossy multiple-coupled transmission lines

Design of high-speed, high-performance electronic circuits requires simulation of transients in networks that include multiple, coupled lossy transmission lines. A widely used circuit simulator, SPICE, does not have facilities for simulation of multiconductor transmission lines. Recently a modification to SPICE3 to include multi-conductor lossless lines was reported. In many situations line losses must be included in the model and networks with lossy transmission simulated. In general simulation of lossy transmission lines is complex and computationally very intensive. The situation is simpler when D-C losses are considered. A recent study concluded that D-C losses provide an adequate modeling of signal transmission in many practical situations. This paper describes the implementation of multi-conductor, coupled lines with D-C losses in SPICE3e2. This implementation ties SPICE transient analysis with a special algorithm for the analysis of a transmission line and is more efficient than another approach based an the concept of a transmission line subcircuit. Internal tests of the new program, LSPICE3, were successfully performed and now this program is available to SPICE3 users