EMI Bites: Why Frequency Dictates Return Paths in PCBs
A common PCB design oversight?
Ignoring how signal frequency shapes return currents, which can spike EMI and degrade signal integrity.
For high-speed signals, return currents follow the path of least impedance, staying directly under the trace where frequency-dependent inductance dominates.
For low-speed signals, the resistive part takes over, driving currents along the shortest path to close the loop back to the source.
Misjudging these paths can lead to larger loops, radiating EMI.
Apply this knowledge to optimize layouts and boost EMC performance.
-Dario
P.S. Want more EMI control strategies to pass EMC?
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