This article presents a design of a high‐performance ultra‐wideband (UWB) bandpass filter with a controllable notched band. Firstly, a UWB filter consisting of a stepped‐impedance resonator (SIR) and two shunt short‐circuited stubs is synthesized. Then, a narrow controllable notched band is introduced by a coupled external SIR. To be highlighted as an attractive advantage, as the characteristics of the UWB filter are not deteriorated by the placement of the external resonator, no further adjustments is needed for the synthesized UWB filter in this design. As an example, an (Federal Communications Commission) FCC UWB filter with a WLAN notch band is designed, simulated, and fabricated. A good agreement between the measured results and predicted ones validates the newly proposed design scheme and the filter prototype. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1842–1846, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25354