Measuring the electromagnetic emissions of integrated circuits with IEC 61967-4 (the measuring method and its weaknesses)

Advances in device technology are progressing at such a rate that the functionality of integrated circuits (ICs) nearly doubles every year. The evolution of device technology has yielded devices with clock rates in the GHz range and rise and fall times in the order of a few pico seconds. Without a proper design, ICs often generate high radiated and conducted emissions. The customer can no longer assume that the system in which modern ICs are implemented will meet the regulatory limits and performance compatibility with other electronic devices. This paper deals with the characterization of the electromagnetic emission of ICs, especially the so-called 1 Ω/150 Ω method (IEC 61967-4) will be used to measure the conducted emission of an EMC test chip. In particular, the problem of this method when applied to measure the emission of a slew rate controlled output driver is discussed. Higher emission results caused by the 150 Ω coupling network (which is not present in conventional applications) have been experimentally evaluated by simulations and measurements.