After a comparison of major strategies of electro-thermal simulation (the relaxation
method and the method of simultaneous iteration) a detailed description of the fundamentals
and realization issues of the simultaneous iteration method is given. The paper introduces
the SISSSI electro-thermal simulation package which is a recent realization of the
latter method, fully integrated into the Cadence Opus design framework. The use of
the package as an analogue circuit layout design verification tool is demonstrated
through a detailed case study.