A Fully Tunable Bandpass Filter Using A Varactor-Tuned Short-Stub Loaded Resonator

In this paper, a two-pole tunable bandpass filter which allows for operational agility of the center frequency and bandwidth is proposed. The fundamental structure is based on a spilt-ring resonator (SRR) with three short-stub tapped. Three sets of varactors are utilized for tuning the center frequency, bandwidth and external quality factor. A frequency tuning range of 0.82-1.54 GHz with a 3-dB bandwidth tuning from 70 to 140 MHz of the proposed filter is realized.