Bibhu Prasad Nayak
Electronic devices generally emit electromagnetic (EM) noise to the surroundings and are also susceptible to the surrounding fields. Electromagnetic compatibility (EMC) is the ability of the systems to function in the presence of electromagnetic environment, by reducing the unwanted field generation and reception of electromagnetic energy which may result in malfunction such as electromagnetic interference (EMT). EMC focuses on two aspects of system behavior, emission and immunity. The main challenge in the case of emission is to identify the noise source in the system and to find out the countermeasures to reduce the emissions without affecting the functionality. On the other hand, immunity is the ability of equipment to function correctly in the presence of electromagnetic noise. Based on this, systems can be classified as the emitter and receptor. Noise can propagate from the emitter to the receptor through the coupling media. Coupling can happen either through conduction by the shared power supply cables between devices or by the direct radiation between them. In board level design, active components like microcontroller, communication ICs are prone to the external noises. PCB traces in the layout provide the coupling paths to the internal or external EM noises. Using a good immunity EMC model for the ICs, an optimized layout can be designed to reduce the level of coupling that increase the overall system EMC performance. Generally, EMC testing is done once porotype is available. Any failure in the test requires design iteration such as addition of extra filter components or layout changes. This causes delay in time to market and eventually loss in revenue. Nowadays EMC simulation-based design is being practiced at concept level to avoid such losses. It is well known that project cost reduces when the EMC simulation and design is brought in the early design phase.
