In this paper, a new switchable bandpass filters based on loaded stepped-impedance resonators (SIRs) and PIN diode switch is introduced. The diode is used to switch the resonant frequency of stepped-impedance resonators between ON and OFF state according to its bias conditions. The designed filter consist of three SIRs with same fundamental frequency and different spurious frequencies in order to have bandpass filters with wide stop band characteristics. The proposed filer shows passband insertion loss of 0.6 dB at 2.35 GHz and provides wide stopband up to 4.75f0 in its ON state. Also, the isolation of filter is better than 30 dB at center frequency and better than 20 dB from dc up to 4.7f0 in OFF state. The comparison between simulation and measurements showed a good agreement.

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