A novel differential-mode (DM) bandpass filter (BPF) on microstrip-line topology with wideband common-mode (CM) suppression is presented. The DM BPF is composed of a pair of half-wavelength (/2) uniform impedance resonators and two coupled-line sections as feeding scheme. By installing an open-circuited stub in the middle of the coupled-line section, spurious CM response can be tremendously suppressed over a wide band. Thus, wideband CM suppression is realised in and beyond core DM passband. Finally, a DM BPF is designed and fabricated to support the proposed design concept.