A compact switchable bandstop filter with dual-band and wideband bandstop functions

In this article, a three-state switchable bandstop filter is proposed, which integrates narrowband dual-band bandstop filter (DBSF), tunable DBSF, and wideband bandstop filter (WBSF) into a topology structure through conducting or disconnecting two p-i-n diodes. Adjusting the capacitance value can change the transmission zero (TZ) and achieve tunable stopband bandwidth. The proposed three-state switchable bandstop filters are simulated and measured. Narrowband DBSF has a 30 dB stopband rejection (SR), tunable DBSF has 6 stopband TZs, tunable stopband bandwidth, and WBSF has a relative bandwidth (RB) of 118.1%. Simulation and measurement results are in good agreement. This switchable bandstop filter meets the requirements of compact RF front-end structure and functional integration.