Single-Ended-to-Balanced Filtering Power Dividers With Wideband Common-Mode Suppression

Four novel architectures of wideband fiveport single-ended-to-balanced power dividers with broadband common-mode suppression are proposed in this paper. The band-pass filtering capability with/without close-to-passband transmission zeros are also incorporated in some of them to obtain multifunctional single-ended-to-differential-mode filtering/power division operation. Two ideal 180 degrees phase inverters are used to replace the conventional half-wavelength transmission line-based inverters in the basic power divider structure so that wideband common-mode rejection and a smaller circuit size are achieved. Quarter-wavelength transmission lines and coupled-line sections are exploited to simultaneously realize the bandpass filtering and wideband power division functionalities. Each five-port power divider exhibits broadband 3-dB single-ended-to-balanced power division, high in-band input-output power-matching levels, high in-band power isolation levels between the two balanced outputs and wideband common-mode rejection. The theoretical analysis, parametric study, and design procedure for the conceived single-ended-to-differential-mode power dividers are provided. Furthermore, for experimental and demonstration purposes, four microstrip prototypes designed at 1 GHz are manufactured and characterized.