The design of a differential‐mode wideband bandpass filter (BPF) with good common‐mode suppression is presented in this article. The structure of the proposed filter is divided to behave like a bandpass or bandstop filter (BSF) under differential‐ or common‐mode operation. The open stubs in the BSF are used to control the 3‐dB bandwidth (BW) of the BPF by slightly reducing the 3‐dB cut‐off BW of the BSF. To validate the design idea, a differential‐mode BPF centered at 4 GHz with a 3‐dB BW of 55%, near 30 dB common‐mode suppression, is designed and fabricated. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:197–200, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27230