The unrelenting movement to higher density integrated circuits continues unabated. Reductions in the size of magnetic components have been achieved by operating at higher frequencies , mainly in switching circuits. Traditionally transformer design has been based on power frequency transformers with sinusoidal excitation. Empirical rules have evolved which generally lead to conservative designs. Non-sinusoidal excitation, at high frequencies. Introduces new design issues : skin and proximity effects in windings and increased กระแสไหลวน (eddy current) และ ความสูญเสียของฮีสเทอริซิส (hysteresis losses) ในแกน . The starting point for optimized design is the assumption that wining losses equal core losses [1,2]. However , in a typical power transformer , the ratio may be as high as 10:1, this is due to the fact that the flux density is limited by its saturation value. At the other end of the frequency scale, the transformer may be operating with a maximum flux density well below its saturation value to achieve an optimum design.