Definition

A power plane is a copper layer dedicated to distributing power supply voltage(s) across the PCB. Power planes form part of the power distribution network (PDN) along with decoupling capacitors. Multiple voltage domains may share a plane with splits or isolated pours. Power planes also serve as reference planes for adjacent signal layers if continuous enough. Effective PDN design minimizes impedance from power supply to component power pins across all frequencies. Plane capacitance (distributed capacitance between power and ground planes) provides high-frequency decoupling.