High current, low equivalent series resistance printed circuit board coil for power transfer application

A smartphone, comprising:

• a housing;
• and
• a wireless charging coil, the coil including a layered structure of electric conductors on a printed circuit board (PCB), wherein the layered structure comprises:
• a first layer including a first electrically conductive trace comprising a first turn and a second turn adjacent to the first turn, wherein the first electrically conductive trace is on the PCB;
• a second layer including a second electrically conductive trace comprising a third turn and a fourth turn adjacent to the third turn, wherein the second electrically conductive trace is overlaid the first layer;
• and
• a plurality of vias coupling the first layer and the second layer, wherein the plurality of the vias include a first via, a second via and a third via distributed along a length of the first turn, each of the first via, the second via and the third via electrically connecting the first turn and the third turn, wherein the plurality of the vias further include a fourth via, a fifth via, and a sixth via distributed along a length of the second turn, each of the fourth via, fifth via, and sixth via electrically connecting the second turn and the fourth turn, wherein the first via, the second via , the third via, the fourth via, the fifth via, and the sixth via are distributed separately in locations other than locations of taps of the first and second trace.