A dual-band MMIC 180° lumped-element hybrid: mixer application

Design formulas for the development of an uncommon 180° hybrid working in two distinct frequency bands are provided. In particular, the design formulas of a lumped-element (LE) rat race, starting from a conventional transmission-line version, are obtained. Moreover, in order to generalize the approach, a matching problem at the input and output ports is taken into consideration, assuming the relevant impedances to be different. Finally, the design of a dual-band 180° LE hybrid, to be used in a singly balanced mixer, is carried out