A Wideband Balanced-to-Unbalanced Coupled-Line Power Divider

A compact wideband balanced-to-unbalanced (BTU) out-of-phase power divider (PD) is proposed in this letter. This novel circuit essentially consists of three pairs of cascaded coupled lines and a grounded resistor for output isolation. By using the even- (odd-) mode method analysis and the traditional transmission-line theory, closed-form design equations for equal power division with out of phase from one differential input to two unbalanced outputs, high output isolation and good common-mode suppression are obtained, simultaneously. In addition, an experimental PD is designed and fabricated. The good performance and the consistency between the simulated and measured results verify our design theory.