2.2 Power and Ground

Use one layer (second layer xc) as a ground plane. Make sure that routes do not break this ground plane. Power can route on all layers except the ground layer. Power supply routes must be heavy copper fill planes to ensure the lowest possible inductance. The power pins of the core IC must have a Via directly connected to the power plane as close to the pin as possible.

Decoupling capacitors must have a Via right next to the capacitor pin, and this Via must go directly down to the power plane; that is, the capacitor must not route to the power plane through a long trace. The ground side of the decoupling capacitor must have a Via right next to the pad, which goes directly down to the ground plane. Each decoupling capacitor must have its own Via directly to the ground plane and power plane right next to the pad. Place the decoupling capacitors as close to the pin for filtering.