Transition from analog to digital technology thus created a change of pace in the growing level of disturbance caused by the increasing integration of transitors into integrated circuits, as predicted by Moore's law (according to which the performance of processors and the number of transistors relating to them, double every 18 months). If, on the one hand, enhanced calculation performance has allowed companies to develop increasingly advanced and complete products, on the other it has added to the difficulties in passing electromagnetic immunity tests. These difficulties include: • increasingly smaller electronic components and electronic boards that are more sensitive to disturbance (especially surges) but also higher emissions with problems concerning reciprocal interference between circuits; • increasingly faster microprocessor clocks with bands over 10 GHz, thus high frequency disturbance making shielding more difficult to achieve;
• increasing numbers of electronic apparatus in every environment with shorter distances between them, thus more interference; • increasingly lower energizing voltage creating more noise; • ever-faster communication networks, even in domestic environments; • wireless communication in almost all devices which, on the one hand, prevents single devices from being totally shielded but on the other, obliges the disturbance of other devices to be considered. Nowadays however, training in terms of courses, books, guides, conferences and assistance from specialized research centers and laboratories helps manufacturers to overcome the growing difficulties and consumers to become more aware and safeguarded. In view of the importance of the problem, EMC is governed world-wide by standards, directives and laws. The terms used for defining compatibility are illustrated in figure 4:
Figure 4: EMC levels
