Design consideration of high frequency planar transformer

Summary form only given. The traditional design rule, E = kB/sub max/ NA/sub C/ f/spl middot/10/sup -8/, for transformers is not completely suitable for the planar transformers operating in high frequency power transfer applications. The voltage applied to the drive winding, E, is proportion to the effective cross-sectional area of the magnetic core, A/sub C/. However, the effective cross-section area is not well defined for planar transformers. Planar magnetic core transformers perform excellent at high frequency applications. Meander windings or spiral windings of planar transformers have problems of proximity effect and unbalanced magnetic flux distribution. Planar transformer with helical winding structure has been found that it can significantly overcome these disadvantages while keeping their advantages New design rule for high frequency planar transformers should be developed to fill the gap between the traditional design rule and the new planar transformers.