High frequency planar transformer with helical winding structure

A high frequency planar transformer with helical windings is proposed. This transformer combines the advantages of the planar magnetic core transformer and air core transformer. The experimental results show that the input impedance and the voltage ratio of this new transformer are much higher than its air core counterpart. The numerical result shows that the flux is evenly distributed and totally enclosed inside the planar ferrite. The electromagnetic interference (EMI), generated from the windings of transformer, is significantly reduced by using magnetic ferrite cores.