Compact differential wideband bandpass filter

A compact differential wideband bandpass filter (BPF) with good common mode suppression is presented in this paper. The proposed filter consists of a four port two stage branch line differential mode filter. This filter is analyzed by bisecting it into a two port network, which results in a bandpass or bandstop filtering response under differential or common mode excitations, respectively. The length and widths of the stubs can be tuned to obtain desired passband and stopband of the differential BPF. The proposed differential filter is fabricated and measured. The measured results are in good agreement with the simulated results.