A Design of Varactor-Tuned Combline Bandpass Filter Using Coupling Varactor Diode |
Byung-Wook Kim, Hyung-Il Back, Sang-Won Yun |
Dept. of Electronic Engineering, Sogang University |
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Abstract |
In this paper, a novel varactor-tuned combline bandpass filter is presented. The coupling varactor diode between line elements is introduced to control the passband bandwidth so that the passband bandwidth can be maintained almost constant within the tuning range. The equivalent circuit and design equations are derived, and the optimum design is discussed. A 1.7 GHz, two-pole bandpass filter with a bandwidth of $4.5%$ was constructed. The absolute passband bandwidth was maintained almost constant within more than 0.4 octave tuning range. |
Key words:
Comb line Bandpass Filter, Constant Passband Bandwidth, Tunable Bandpass Filter |
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