Compact High-Performance Balanced Wideband BPF With a Notch Band and Multiple Transmission Zeros

In this letter, a novel compact high-performance balanced wideband bandpass filter with a notch band and multiple transmission zeros (TZs) based on double-sided parallel-strip line (DSPSL) structure is proposed. Compared with the half-wavelength microstrip lines, an intrinsic excellent common-mode suppression (CMS) can be realized with a small circuit size in the DSPSL structure. The wideband filtering responses are first constructed by using a short stub-loaded multimode resonator. The shorted coupled lines are utilized to introduce extra TZs on account of the transversal signal interference technique. The asymmetric three-line coupled structures are employed to create a notch band around 3.0 GHz to avoid inference signals. One filter prototype is designed, manufactured, and measured to validate the framework principle.