Resistive vs. Inductive Return Current Paths

摘要

It is well known and understood that at high frequencies return currents will find the path of least impedance to return to their source. What may not be well understood is where frequencies become 'high frequencies'!rnIn reality, return current will always follow the path of least impedance. At lower frequencies, this means the path of least resistance and at high frequencies, this means the path of least inductance. The change over frequency can be surprising low. A simple example to illustrate the change over frequency calculation can be obtained using a simple microstrip trace over a ground-reference plane on a PCB.