A Compact Balanced-to-Balanced Filtering Gysel Power Divider Using λ g /2 Resonators and Short-Stub-Loaded Resonator

In this letter, a compact balanced-to-balanced filtering power divider (FPD) is presented. It is composed of three half-wavelength resonators and a short-stub-loaded resonator (SSLR). Due to the intrinsic resonance characteristic of the half-wavelength resonator, the bandpass response and power dividing function for differential-mode signal are realized and the suppression for common-mode signal is also achieved. The SSLR is utilized as an extra isolation resonator to achieve high isolation between two output ports. A resister is also needed to load on the SSLR for adjusting its loaded quality factor (Qe). For the demonstration of the design method, an FPD operating at 2.405 GHz has been fabricated and measured. The measured results validate the design method.