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PCB Board Circuit Board Design How To Prevent EMC Doubt
Jul 01, 2017

  PCB board circuit board design how to prevent EMC doubt

  Recently, I was asked about EMC's questions, such as how to plan to prevent EMC's question, I often often pay attention . shoes with the time will certainly ask this question. First of all, this is a systematic question, not so good answer, especially for high-speed signal gathered in this category rather than the EMC long-term high-speed gentlemen who would have been able to answer only about, tell the truth, in the EMC category we also Still in continuous learning, so this article is only based on our understanding of some of the EMC, PCB board from the PCB factory plan to try to prevent the onset of doubt, during which is not the bit also asked us to criticize the correction, If you have a very good article, but also look forward to submission to us.

  At the beginning of the article said, EMC and SI, PI information related to many times we will inform us that we can not carry out EMC simulation, but we will try to prevent some of the board from the EMC question, that white Try to ensure SI and PI functions, from the source to prevent EMC queries.

  First, for the integrity of the signal and the relationship between EMC Chen has written a lot of articles in front of some of the truth, today we come to a brief summary, SI attention to overshoot, reflection and crosstalk, and EMC has a direct contact. The signal due to poor impedance matching, will attack a variety of reflections, reflection will have a larger overshoot, then the overshoot amplitude in addition to the impact of the life of the equipment, but also affect the radiation, because he Is the origin of radiation, so the PCB board planning on the key signal on the need to try to control the impedance, so that impedance matching, and perhaps the case also need to go through a certain external termination to reach the match, in the topology and termination of the series has been Talked about a variety of termination methods; in addition to the need to pay attention to the signal cross-cutting questions, the signal cross-cutting In addition to the impedance question, there is always the signal back to the doubt, when the signal back, many people will think of EMI, Yes, the signal return path will also become an issue of EMI doubt; then there is crosstalk, crosstalk that is the coupling between the signals, many people may be directly and EMI equivalent to prevent crosstalk need to increase the signal The distance between, in particular, the microstrip line, the other also need to think about the crosstalk between the double stripline, try to prevent the parallel stacking too long; there are some Board edge alignment, along the cutting line, etc., which are some of the cliche of the topic, but easy to understand, if there is a certain sense of planning in the SI and from the SI point of view to plan, then many of the EMC-related questions Would have been able to prevent.