Transformer-less ladder network design with non-minimum impedance functions

Abstract

In this study, a new method of design for transformer-less ladders is introduced. It has been shown that, given a non minimum impedance function which includes finite transmission zeros (FTZs) can be synthesized without transformers. The parametric form of non-minimum impedance function is constructed by cascading a dummy Foster part reactance and a minimum part impedances. The synthesis procedure starts with extraction of Foster part then the minimum part. Even the negative inductors are occurred while extracting FTZs as Brune sections it is shown that, all negative elements are eliminated by the positive valued inductors of adjacent Brune sections. If the impedance function has been only composed of a minimum part impedance then it will not possible to obtain this conclusion. Therefore the proposed parametrical construction provides transformer-free ladder network topologies. Real Frequency Technique is incorporated to optimize the realizable impedance over the band of interest. An low pass (LP) design example is presented.