Filtering balanced/balanced-to-single-ended networks

Balanced/balanced-to-single-ended networks have been used widely in modern communication systems due to their ability of easy connection in balanced systems as well as differential-mode power division, common-mode suppression. Furthermore, filtering balanced or balanced-to-single-ended networks have become increasingly of interest for the advantages of multiple functions and compactness. In this paper, the filtering balanced-to-single-ended power dividers and the balanced branch-line couplers realized by replacing the transmission line structures with filtering structures are reviewed and discussed.