In this paper, a super ultra-wideband (UWB) bandpass filter (BPF) with frequency bandwidth from 3.0GHz to 22.5GHz (-10dB-return loss bandwidth), which is much wider than that of the conventional UWB BPF, was proposed and demonstrated. The filter employed a simple and compact broadside-coupling structure. Simulation, fabrication, and measurement were carried out. The developed filter has good performance: 0.74dB insertion loss at central frequency (about 12.5GHz), and 0.2ns group delay over main passband. It was confirmed in this work that the conventional technique of multistage was applicable to improve the skirt performance, even for such a super wide bandwidth. To author's best knowledge, the developed super UWB BPF is the widest bandwidth filter in the world.