With the development of Ultrabook in recent years, the main and auxiliary antennas for WLAN are moved down to PC base because the LCD panel is too thin to install antennas inside. On top of that, there are also more and more laptops equipped with super high-speed USB 3.0 ports. Unfortunately, the USB 3.0 modules will usually radiate the EMI noise to affect the receiving performance of WLAN in the Ultrabook if USB dongle is inserted or the USB cable is plugged in. To analyze and quantify the effect of the USB 3.0 EMI noise on the WLAN performance of Ultrabook, several experiments have been conducted for relationship between throughput rate and EMI noise power received by the antennas. Some equipment utilized will be presented in this paper, which have been developed to help trouble-shooting and identifying the root cause of EMI problem relevant to the radiated EMI noise from various IC chips, modules, devices, and so on. In addition, the EMI diagnosis procedure also applies to other high speed modules such as HDMI, LVDS, SATA, PCI Express, Display Port, and EDP. Finally, the possible solution to USB 3.0 EMI problem will also be discussed.
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