Compact thermal models: Assessment and pitfalls

Thermal analysis involves solving a differential equation, thus inherently takes a long time. Any thermal optimization techniques require a compact model that can be evaluated fast while accuracy is not sacrificed too much. Several models have been proposed, but their accuracy and runtime have not been fully understood and compared. Three models, namely resistive network, heat diffusion measure, and thermal signature, are studied; a series of experiments reveals that thermal signature is clearly a model of choice. Power density is a key parameter in thermal analysis, and is usually given as a constant value, which corresponds to the average over the region a block occupies and over the time period it operates. The error as a result of approximation is often unnoticed; this is studied in a quantitative way for the first time.