Inductance of printed circuit board ground planes

A derivation of the inductance of a large ground plane is given. Some practical situations, such as the ground inductance of bilayer and multilayer printed circuit boards (PCBs) and the impact on the common mode radiation, are described. The ground inductance which results in a much higher ground impedance than only the AC resistance does is determined. The inductance of a PCB track and therefore the radiated emission level can be lowered by broadening the track to a plane or creating a better coupling by reducing the distance between signal and return track. A multilayer PCB is better than a bilayer PCB. The net result is a factor of 10 (=20 dB) lower ground impedance per layer doubling.<
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