Novel Synthesis Method for Wideband Filter with Additional Insertion Phase

In this article, a novel synthesis method for wideband bandpass filters (BPFs) with integrated arbitrary phase shift (PS) is proposed. This design introduces nonresonating nodes (NRNs) at the input and output ports, forming a new wideband BPF configuration. An admittance matrix is constructed to describe the filter, where the desired PS is controlled through termination-related couplings and the selfcouplings of the first and last resonators. Moreover, to implement the BPF with lumped elements, an ABCD matrixbased circuit transformation is introduced, which eliminates the need for input/output J-inverters, thereby overcoming their bandwidth limitations in wideband BPFs. To validate the proposed design method, a wideband BPF circuit with a PS range of 120° is designed, fabricated, and measured. The circuit exhibits a passband from 1 to 2.2 GHz, corresponding to a fractional bandwidth of 80.9 %. The measured results align closely with simulated data, demonstrating the effectiveness of the proposed method in achieving the desired PS performances.