Tunable Combline Bandpass Filter Using Cross-Coupled Stepped-Impedance Resonators with Enhanced Characteristics |
Yoon-Hong Kim, Young-Ho Cho, Sang-Won Yun |
Dept. of Electronic Engineering, Sogang University |
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Abstract |
This paper proposes a tunable combline bandpass filter with high selectivity, constant bandwidth, and good stopband performances. A filter with these characteristics is obtained by applying cross-coupling to the conventional combline bandpass filter using stepped-impedance resonators(SIRs). For high selectivity and constant bandwidth, cross-coupling is utilized and the SIR configuration is used for enhanced stopband performances. The proposed combline tunable bandpass filter with 5% of fractional bandwidth at 1.6 GHz was fabricated and tested. The measured results showed 11.6% tunability with constant bandwidth, high selectivity and enhanced stopband characteristics. |
Key words:
Combline Filters, Stepped-Impedance Resonator, Cross-Coupling, Microstrip Filters, Transmission Zeros, Tunable Filters |
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