The paper deals with the evaluation of the far-field radiated emissions from high-speed interconnects when the frequencies are such that the distribution of the currents along the traces is no longer of TEM-type. Instead of a computationally expensive numerical full-wave model, here a generalized transmission line model is used to obtain the current distributions. This full-wave transmission line model is derived from an integral formulation and is here extended to include in efficient way the layered media Green's Functions. The proposed tool is successfully benchmarked to references given in literature and case-studies of practical interest are carried out, referring to a coupled microstrip, driven either by differential and common mode currents. This analysis highlights the existence of a transition range where the error made by evaluating the emission using the classical transmission line current distribution is still negligible.
EMI/EMC in printed circuit boards-a literature review | IEEE Journals & Magazine | IEEE Xplore
At high frequencies depending on the length of the interconnects and the current carried by the conductors, the interconnects tend to act as antennas, resulting in EMI. These EMI radiations interfere with other devices present in the vicinity. There are international standards that limit the level of emissions. Thus, it is highly important to measure electromagnetic radiation and control these radiations. Whether it is within the set standards? EMC ensures that the system must perform as intended under the defined safety measures.
5 EMI/EMC Design Considerations for Optimal PCB Manufacturing
The use of decoupling capacitors connected between the power and ground planes on a printed circuit board PCB is a common practice to help ensure proper functionality and to reduce EMI emissions from printed circuit boards. The proper number of decoupling capacitors, and the proper value of those decoupling capacitors is always a topic of debate between EMC engineers and design engineers. Some typical rules-of-thumb require a decoupling capacitor for each power pin on an IC. Other rules-of-thumb require at least one decoupling capacitor per side of physically large ICs.
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