Novel formulation of efficiency measure for multifilar transformers in generalized multiport configurations of integrated passive devices

This article formulates generalized transformer efficiency associated with the application of above-IC multifilar transformers to multiport integrated passive devices (IPDs). The formulation derives the power-loss ratio for a multifilar transformer in a multiport configuration based on a terminated microwave network, leading to the expression of passive efficiency using the concept of power conservation. For demonstration, the S-parameters for several different types of three-port transformers have been measured to compute their passive efficiency and, further, predict the minimum available insertion loss of three-port IPDs such as baluns and combiners that use these three-port transformers. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:656–661, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26656