Integrated RF tunable filter based on recursive architecture and its application

This paper reports development of an integrated tunable filter for lower UHF band based on the recursive architecture and its application. The recursive filter core gives the 2-pole bandpass response, and its center frequency can be tuned from 250 to 500 [MHz]. The auto setting mechanism was developed for the filter center frequency and passband width. Higher order filters were synthesized by combining multiple cores. A simple spectrum scope was constructed as a demonstration.