Filtering Power Divider With Arbitrary Prescribed Phase Difference

This paper presents a design of filtering power divider with the arbitrary prescribed constant phase difference between two different paths. The proposed circuit consists of a Wilkinson power divider (WPD) and Nth-order coupled line bandpass filters (BPFs) with different fractional bandwidths (FBWs). Closed-form design equations are derived for the efficient design of the proposed circuit. By controlling the FBWs of the BPF, the phase slope can be controlled, which can provide a flat phase difference over a wideband. For experimental validation, the proposed circuit was designed and measured at a center frequency of 2.90 GHz with 180° phase difference. The simulated and measured results coincide well with the theoretically predicted performances.