High-Q intrinsically-switched quasi-absorptive tunable bandstop filter with electrically-short resonators

Abstract

Tunable high-Q intrinsically-switchable quasi-absorptive bandstop filters are presented in the 4 GHz to 6 GHz and 6.3 GHz to 11.4 GHz frequency ranges. Their responses can be reconfigured between all pass and tunable bandstop filter responses by simply tuning the center frequency of their resonators, avoiding insertion loss and control voltages associated with the series switches required in conventional bandstop filter banks that have similar response reconfiguration capability. In contrast to previously shown intrinsically-switchable bandstop filters, the filters shown in this paper require only one tuning element per resonator, have a significantly higher quality factor (650), and use electrically-short resonators. When combined with destructive interference attenuation enhancement techniques, these characteristics enable >60 dB maximum attenuation in the bandstop state and less than 2.0 dB insertion loss in the all pass state.