Balanced-to-Balanced Gysel Power Divider With Bandpass Filtering Response

In this paper, the balanced-to-balanced Gysel power divider is proposed with bandpass filtering response for the first time. The component is based on a ring structure and designed with an extended coupled-resonator circuit model. The characteristic impedances, electrical lengths, and isolation resistance are calculated analytically by our derived equations, according to the design specifications of the filtering power divider. The achievable bandwidth is from about 3% to 12%. As an example, a fabricated prototype occupies an area of 0.97 × 0.87 λg
²
, whose bandwidth is 8.4%. It has low differential-mode in-band insertion loss, good magnitude, and phase balances between two output ports, good isolation, and good suppression of common-mode noises and mode conventions. Based on stub-loaded sections, another prototype is realized for miniaturization, whose occupied area is reduced to 0.67 × 0.63 λg
²
. In comparison with the original prototype, the central insertion loss is increased by 0.13 dB, and the rejection band of common-mode and mode-conversion noises is narrowed by 21%.