A Design of Tunable Band Pass Filter using Varactor Diode

This paper proposed a tunable band pass filter. It is two-poles direct capacitive coupled resonator band pass filter which the capacitors of parallel resonators are changed by varactor diodes. The DC bias controls to change the value of capacitance in the parallel resonator for tunning the pass band. To validate the proposed design method, we fabricated the band pass filter which has tunable center frequency from 200MHz to 245MHz.