Denis Griot is CEO for Freescale Semiconductor Toulouse, France. He has been instrumental in the creation of the Crolles2 Alliance, one of the largest R&D alliance in the industry. He holds five semiconductor patents. He earned master’s degrees in solid-state physics and nuclear physics respectively from INSEA Lyon and INPG Grenoble, France.
The objective of the invited talk is to provide an overview on abilities, limits and possible solution paths of near field scanning techniques applied in EMC and Immunity. In most cases these techniques are used for one of the following four purposes:
If the objective is to predict system level emissions one could, at least in principle determine the fields around a system and use near-to-far field transformations. However, it is difficult to obtain the fields completely. For example, cables might exit the PCB. The near-to-far field transformation is sensitive to position and value uncertainty, especially, if only a few of the 6 possible field components have been measured.. An alternative path is to obtain local values e.g., dipole moments or reconstructed currents that are then placed as sources into full wave simulations. This is further complicated by the lack of phase information in complex digital systems, difficult to obtain during scanning due to long software cycling times.
Susceptibility scanning, e.g., for analyzing ESD or radiated immunity behavior will identify many sensitive areas on a PCB, however not every sensitive area will couple to external fields equally well. Coupling to the fields as they are present in system level testing or during ESD testing needs to be analyzed. Here resonating structures enhance the coupling at specific frequencies. Those structures, their resonating frequencies and Q-factors can be identified by resonances scanning, helping to close the gap between local and system level behavior. Another area of constant improvement is scan speed and probing methods. The talk attempts to provide an overview of the problems and solution paths presented by different researchers in this area.