Electromagnetic compatibility (EMC) refers to the ability of a device or system to operate according to the requirements of its electromagnetic environment without causing intolerable electromagnetic interference to any equipment in its environment. Therefore, EMC includes two requirements: on the one hand, it means that the electromagnetic interference generated by equipment during normal operation cannot exceed a certain limit; On the other hand, it means that electrical appliances have a certain degree of immunity to electromagnetic interference in their environment, that is, electromagnetic sensitivity.
The requirements of EMC design are as follows: ① Clear the EMC index of the system. The electromagnetic compatibility design includes the electromagnetic interference environment in which the system can maintain normal operation and the allowable indicators of the interference of the system to other systems. (2) On the basis of understanding the interference source, the interfered object and the interference mode of this system, these indicators are allocated to each subsystem, subsystem, circuit, components and devices step by step through theoretical analysis. (3) According to the actual situation, take corresponding measures to suppress interference sources, eliminate interference channels and improve the anti-interference ability of the circuit. (4) Verify whether the original index requirements are met through experiments. If not, further measures will be taken and repeated until the original index is reached.
High-speed PCB design is also a very complicated design process, and many factors need to be considered in the design. Such as timing requirements, stripline stripline and microstrip microstrip, signal matching scheme, signal quality, signal routing topology, power supply decoupling, current return path of high-speed signal return, signal impedance control and stack control, single board EMC/EMI strategy analysis, blind vias and buried holes, etc. These factors are sometimes opposite: for example, the proximity of high-speed devices in layout can reduce the delay, but it may produce crosstalk and significant thermal effects. Therefore, in the design, we weighed various factors and made a comprehensive compromise: it not only met the design requirements of high-speed PCB, but also reduced the complexity of the design. (Source: www.pcbwok.net)