Simulation of self-heating in advanced high-speed SiGe bipolar circuits using the temperature simulator TESI

Advanced SiGe bipolar technologies now allow the realization of very-high-speed IC such as 40 Gbit/s multiplexers and 77 GHz automotive radar VCO, even if high output power levels are required. However, in such circuits self-heating often leads to high peak temperatures. This can decrease transistor performance and circuit lifetime and must, therefore, be considered during circuit design. In this paper we demonstrate how the temperature increase resulting from self-heating can be accurately determined already in the design phase. For this, we present the experimentally verified three-dimensional numerical temperature simulator TESI that was specifically developed for such problems. It is shown how this tool can be applied to investigate practical circuits using the core of a 40 Gbit/s power multiplexer and the buffer stage of a 77 GHz VCO with high output power as examples.