In this work, a novel UWB differential ultra-wideband (UWB) power-distribution network is presented. By properly converting four-port balanced filter to a three-port balun filter, a differential power-distribution network integrated with two balun filters can be realized. To demonstrate the idea, a prototype centered at 4 GHz for lower band of UWB (3.1-4.85 GHz) is designed and fabricated. The selective differential-mode passband response with 45% bandwidth and wideband common-mode rejection which is greater than 20 dB is obtained. The phase and amplitude imbalances are 180° ± 2° and 0.1 ± 0.2 dB, respectively.