Fully tunable filter design using tunable transformers and multiple mode resonators

Abstract

A fully tunable bandpass filter using tunable transformers and multiple mode resonators (MMRs) is proposed. The proposed tunable MMR makes it possible to realize wide-band tunable filters. Thus the tuning ranges of the center frequency and bandwidth are wide. The novel tunable transformer may help to get the desired external quality factor (Qe) while the center frequency or bandwidth is tuned. Thus a good passband performance may be got.