This work presents extremely compact dual-mode and dual-band bandpass filter designs based on dual-resonance composite resonators developed by using integrated passive device (IPD) technology on a glass substrate. A dual-mode bandpass filter is also devised using a symmetric composite resonator with a perturbation element of grounding inductor to determine the filter bandwidth. Additionally, a feedback capacitive coupling path on the proposed dual-mode filter is implemented to produce three transmission-zero frequencies in the stopband. Furthermore, the proposed dual-band bandpass filter is designed in a high-density wiring transformer configuration with magnetic and electric mixed coupling. In addition to individually determining the fractional bandwidth of dual passbands, the magnetic and electric mixed coupling provides multiple transmission zeros to enhance the isolation between the two passbands and greatly improve the stopband rejection.
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