Internal Power Loss Formulas of Lumped-Element Matching Circuits for High-Efficiency Wireless Power Transfer

Kyohei YAMADA  Naoki SAKAI  Takashi OHIRA  

IEICE TRANSACTIONS on Electronics   Vol.E99-C   No.10   pp.1182-1189
Publication Date: 2016/10/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E99.C.1182
Type of Manuscript: Special Section PAPER (Special Section on Microwave and Millimeter-Wave Technology)
wireless power transfer,  impedance matching,  Q factor,  internal loss,  formulation,  

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Internal power losses in lumped-element impedance matching circuits are formulated by means of Q factors of the elements and port impedances to be matched. Assuming that Q factors are relatively high, the above mentioned loss is expressed by a simple formula containing only the tangents of the impedances. The formula is a powerful tool for such applications that put emphasis on power efficiency as wireless power transfer. As well as the formulation, we illustrate some design examples with the derived formula: design of the least lossy L-section circuit and two-stage low-pass ladder. The examples provide ready-to-use knowledge for low-loss matching design.