Patent ID: 8013708

Claim:
A planar transformer comprising: a printed circuit board (PCB) comprising a plurality of primary circuit layers, a plurality of secondary circuit layers, and a through hole passing through the PCB for receiving a core; at least one first winding turn arranged on each of the plurality of primary circuit layers around the through hole, the at least one first winding turn of the plurality of primary circuit layers are coupled in series to form a primary winding; and a second winding turn arranged on each of the plurality of secondary circuit layers around the through hole, wherein a first half of the second winding turn functions as a first secondary winding turn, and a second half of the second winding turn functions as a second secondary winding turn, a node between the first and second halves of the second winding turn is grounded, the first secondary winding turns of the plurality of secondary circuit layers are coupled in parallel to form a first secondary winding, the second secondary winding turns of the plurality of secondary circuit layers are coupled in parallel to form a second secondary winding.