Design of IPD-based wideband bandpass filter chips with controllable transmission zeros

In this brief, two novel wideband bandpass filter (BPF) chips with independently controllable transmission zeros are proposed. BPF I uses bridge T-type highpass and lowpass structures cascaded to achieve wideband filtering. On this basis, BPF II adds three pairs of LC resonant circuits to add additional transmission zeros while retaining the lowpass structures. The analytical methods of odd-even mode and ABCD matrix to S-parameter matrix are used to analyze and calculate two designs. For validation, two prototypes of proposed BPFs in integrated passive device (IPD) have been designed, fabricated, and measured. One prototype operates at 5.3 GHz, providing a 3-dB fractional bandwidth (FBW) of 46.9%, while the other prototype operates at 4.7 GHz, providing a 3-dB FBW of 57.6%. Moreover, the two chips exhibit minimum insertion losses of 1.55 dB and 1.5 dB, respectively, while occupying compact sizes of 2.27 mm x 0.83 mm and 1.7 mm x 0.88 mm.