Display to main-board grounding design methodology through eigen simulation
This paper discusses the grounding between wireless displays and Main Logic Boards (MLB), when they are aligned in parallel to each other to save space. The MLB accommodates lots of high-speed signals such as DDR, MIPI, etc. High speed signals can exploit the display/MLB parallel arrangement to efficiently radiate EM interferences causing wireless system compliance failures and desensitizing the receiver. RF engineers use conductive posts to short the two at multiple points in order to reduce the unwanted radiation. Often this implementation is done using trial and error approach. This paper describes a systematic method to simulate and design the grounding locations to minimize the interference. A design example is presented using this method to reduce the coupling from the noise sources to the antennas by ~40 dB. Without loss of generality, the method can be equally used in similar metal/metal arrangements.