【電磁技術在線】【EMC篇】- 7. 高速RE
講師：Timo Baruth
00：40 內容概覽
01：20 仿真vs測量 概覽
03：00 發射輻射 （RE）仿真方法
09：15 演示PCB：信號模型
13：45 演示PCB：仿真vs測量 部分吻合
15：00 演示PCB：信號加電源模型
15：45 演示PCB：仿真vs測量 全部吻合
16：30 線纜，連接器，PCB，互聯模型
Comparon of simulation and measurement is always a hot and challenging topic. For this case, we use a realistic demonstrator board. This board was layouted and measured at FESTO, which is a leading world-wide supplier of automation technology and the performance leader in industrial training andeducation programs.
We have used this board already for last years webinar where we have studied DC/DC converter and single ended radiation. Fortunately such a board offers a lot of possible effects that can be analyzed and simulated. The board consist of two layout placed on the same substrate. It is basically two boards: one with a good EMC design and one with a bad EMC design. Both design use the same driver components but the layout is quite different.
We can continue the comparison by applying a signal in Design Studio. We apply an ideal rectangular pulse with a frequency of 250 MHz, a level of 1.2V and arise/fall time of 100 ps. Even if we have used an ideal signal in the simulations you can see that the agreement of the measurement and simulation is quite good for the 250 MHz and the 750 MHz, but there is a deviation at 500 MHzand 1000 MHz. Wait a minute! Shouldn’t a rectangular signal only have odd harmonics ??? So where is the 500 MHz coming from? Most probably it comes from the Power/Ground System of the PCB! If your PCB has a poorly design Power Delivery Network it might also become a source of radiation. And this radiation will be at the even harmonics of your signal!
