Novel Synthesis Method for Wideband BPF With Additional Insertion Phase Shift and True Time Delay

In this article, a novel synthesis method for wideband bandpass filters (BPFs) that integrate arbitrary phase shift (PS) and true time delay (TTD) is proposed. The design introduces nonresonating nodes (NRNs) at the input and output ports, forming a new wideband BPF configuration. An admittance matrix is constructed to model the filter, where the desired PS and TTD are controlled through the termination-related couplings and the self-couplings of the first and last resonators. By calculating these coupling elements at the input and output ports, the admittance matrix governing PS and TTD can be synthesized efficiently. Moreover, to implement the BPF with lumped elements, an ABCD matrix-based circuit transformation is introduced to eliminate the need of input/output J-inverters, thereby overcoming their bandwidth limitations in wideband BPFs. The proposed method is validated by designing, fabricating, and measuring a wideband PS BPF circuit with a PS range of 120° and a wideband TTD BPF circuit with TTD range of 320 ps. Both circuits exhibit a passband from 1 to 2.2 GHz, corresponding to a fractional bandwidth of 80.9%. The measured results align closely with simulation data, demonstrating the effectiveness of the proposed method in achieving the desired PS and time delay performances.