High-Selectivity Balanced-to-Unbalanced Filtering Power Divider

A new type of wide-band differential-mode -to-single-ended filtering power divider is presented in this paper. It makes use of half-wavelength ring resonators and coupled-line sections to realize high common-mode suppression within a broad frequency interval. A proof-of-concept microstrip prototype for the proposed circuit that operates in the 1.7-2.7-GHz 4/5-Generation (4/5G) Long-Term-Evolution (LTE) band is manufactured and measured. It features state-of-the-art performance metrics for this RF component in a reduced circuit area of about $0.5\lambda_{\text{g}}\times 0.5\lambda_{\text{g}}$. They include a broad balanced-to-single-ended upper stopband and high common-mode rejection up to four times their center frequency.