Recent advances in reconfigurable microwave filter design

Next-generation multi-mode RF transceivers will require fully-adaptive, high-frequency filtering components with increased levels of spectral agility. Highly-selective single/multi-band filtering actions for various signal-band selection processes and flexible bandstop filtering functions for dynamic interference mitigation will be highly desirable in these systems. Taking into consideration the aforementioned needs, recent advances in the field of adaptive-transfer-function filters are reported in this paper. Specifically, multi-band bandpass filters (BPFs) with tunable passbands, circuits with selectable BPF and bandstop-filter (BSF) operational modes, and broad-band BPFs with incorporated in-band controllable notches are presented.