Date Added: Sep 2011
In today?s communication systems the demand for tunable filters with high performance and with independent control of the filter parameters has been growing. In this paper an overview of several tunable filters that have been proposed over the last years is presented, focused on recent developments involving independent frequency, bandwidth and selectivity control, and high resonator Q filters. Switchable filters are a key component in compact frequency agile communication systems; they allow selecting different bands of operation using a single filter with embedded tuning elements. Fine tuned filters can adapt an optimum filter response to compensate small variations in filter response caused by climate changes or fabrication tolerances.