A 1.9-2.6GHz Filter with Both Bandpass-to-Bandstop Reconfigurable Function and Bandpass-and-Bandstop Cascading Function

摘要

In this paper, a novel tunable filter with multiple tuning functions is proposed. The filter can be used as a 4th-order bandpass-to-bandstop reconfigurable filter for passband or stopband tuning, and also as a 2nd-order bandpass filter cascaded by a 2nd-order bandstop filter for passband tuning with controllable transmission zeroes. In each mode, both the frequency and bandwidth can be controlled within a wide range, demonstrating excellent tuning flexibility and capabilities. The filter topology is expected to find applications in modern wireless standards such as carrier aggregation and cognitive radios.