A balanced-to-balanced filtering gysel power divider with unequal power division

A balanced-to-balanced Gysel power divider is proposed with bandpass filtering response and unequal power division. Design equations are provided for the proposed component, according to the power division ratio and filter specifications. Large design flexibility, small circuit size and low insertion loss can be achieved simultaneously. A microstrip prototype is developed at f₀=2 GHz with a second-order Chebyshev bandpass response. The bandwidth is 8% and the power division ratio of differential-mode outputs is 1:3. The phase difference is smaller than 5°. The suppression of in-band common-mode transmission and mode conversion is over 25 dB. Our idea is validated by the good agreement obtained between the measured and simulated results.