earticle

영어

This paper proposes a 4-pole tunable absorptive dual-notch filter. The absorptive responses at two notch frequencies are achieved using a coupled-line with a lumped inductor and a finite Q varactor. Additionally, the two notches can be independently controlled by adjusting three loading capacitances of the resonator. A 4-pole filter was designed and fabricated on a substrate with a height of 25 mils. The filter demonstrated measured return losses of 5.5–10.2 dB and 8.1–20.2 dB at 0.68–0.96 GHz and 1.11–1.39 GHz, respectively. Applications include cognitive radio systems and carrier aggregation systems utilizing two transmission frequencies. In the future, RF MEMS switching capacitors are expected to significantly improve insertion loss, power handling, and linearity.