A SALIENT DIFFICULTY IN THE DESIGN OF HIGH-FREQUENCY INDUCTORS AND TRANSFORMERS IS EDDYCURRENT EFFECTS IN WINDING. THIS EFFECT IS CONTROLLED BY USE OF “LITZ WIRE”. ALTHOUGH AC RESISTANCE DECREASED BY USE OF LITZ WIRE, BUT DC RESISTANCE INCREASE AS A RESULT OF THE SPACE OCCUPIED BY INSULATION. IN CHOOSE OF LITZ WIRE STRUCTURE, AC AND DC RESISTANCE MUST BE OPTIMALLY MINIMIZED. BECAUSE OF HIGH COST, AN APPROXIMATION OF NORMALIZED COST IS COMBINED WITH LOSS ANALYSIS TO FIND OPTIMALLY TRADE OFF COST AND LOSS. ALSO IN END OF THIS PAPER A PRACTICAL EXAMPLE EXPLAINE CHOOSING LITZ WIRE IN LINE FILTER OF DIGITAL PLC.