Improving Electro-Magnetic Interference of Embedded Systems Through Jittered-Delay Desynchronization

ICs are required to satisfy always increasing performance needs for modern electronic applications. This results in higher operating frequencies for digital circuits, thus increasing the generated Electro-Magnetic Interference (EMI). International standards and industrial regulations, in domains such as automotive applications, enforce strict rules about the EMI behavior of electronic systems. Thus, EMI is becoming a major concern for designers, with direct implications on the commercial viability of a product. In this paper, we apply the desynchronization methodology, down to the physical layout level, to an industrial microprocessor used in automotive applications. The results show that we can both use the advantages from desynchronization, i.e., average case performance and better variability tolerance, and achieve significant EMI reductions, without excessive costs in area or power consumption. While our paper confirms earlier claims that indeed asynchronous circuits reduce EMI, it also shows clearly that by far the largest EMI gain can be obtained by adding dynamically varying delays (which in turn cause local clock jittering) on top of desynchronization.