Issue link: https://iconnect007.uberflip.com/i/1359517
APRIL 2021 I DESIGN007 MAGAZINE 37 need to understand is that the EM energy used in the circuit travels in the dielectric, not the conductors. e PCB conductors are used to create the boundaries for the spaces where the EM fields will go. Managing these spaces starts with the board stackup. If at all possible, there needs to be a solid ground plane between each pair of signal/power layers. ese form a triplet (signal-ground-signal) or a paired dielectric, which allows routing between the two conductor layers to be done with only the signal via. e opening around the via in the ground plane provides the connection between the top and bottom dielectric layers. For example, in a four-layer PCB, if layer two is ground, then layers one and three form the boundaries for the paired dielectrics between them. In this case, layer four is not adjacent to the ground plane, and must be treated as if it were single layer board. Each signal trace needs to be routed next to a ground trace or ground flood area. When connecting layer Figure 3: Images depicting the movement of an EM field as a switch closes. There are only three things that you can do with EM fields: Store them, move them, or convert them into kinetic energy. Figure 4: Moving EM signals often involves some clever routing and via placement, but it's not rocket science. (Images courtesy of Rick Hartley, consultant)