A new balanced bandpass filter (BPF) with tunable bandwidth using tri-mode stub-loaded resonators is proposed. To tune the differential-mode bandwidth, the two even-mode resonance frequencies and two transmission zeros (TZs) are tuned while the odd-mode resonance frequency keeps unchanged. To realize high selectivity for differential mode, another two TZs are created by the source-load coupling and coupling sections. Furthermore, wideband common-mode (CM) suppression is achieved. The fabricated filter has 3-dB fractional bandwidth ranging from 20.0% to 26.0% centered at 1.71 GHz and wideband suppression (17 dB from 2 to 4.4 GHz) for the differential mode, as well as common-mode suppression better than 20 dB from 0 to 4.5 GHz.
2. Tu, W.-H., "Compact low-loss reconfigurable bandpass filter with switchable bandwidth," IEEE Microw. Wireless Compon. Lett., Vol. 20, 208-210, 2010.
doi:10.1109/LMWC.2010.2042553
3. Miller, A. and J.-S. Hong, "Cascaded coupled line filter with reconfigurable bandwidths using LCP multilayer circuit technology," IEEE Trans. Microw. Theory Tech., Vol. 60, 1577-1586, 2012.
doi:10.1109/TMTT.2012.2189242
4. Lu, X., K. Mouthaan, and T. S. Yeo, "A filter with reconfigurable band edges using dual-behavior resonators," Eur. Microw. Conf., Vol. 44, 1592-1595, 2014.
5. Sanchez-Renedo, M., R. Gomez-Garcia, J. I. Alonso, and C. Briso-Rodriguez, "Tunable combline filter with continuous control of center frequency and bandwidth," IEEE Trans. Microw. Theory Tech., Vol. 53, 191-199, 2005.
doi:10.1109/TMTT.2004.839309
6. Kimura, T., H. Kobayashi, and Y. Kishimoto, "Bandwidth-tunable filter consisting of SAW resonators and BaSrTiO3 varactors directly fabricated on a LiTaO3 wafer," IEEE International Ultrasonics Symposium, 795-798, 2014.
7. Serrano, A. L. C., F. S. Correra, T. P. Vuong, and P. Ferrari, "Synthesis methodology applied to a tunable patch filter with independent frequency and bandwidth control," IEEE Trans. Microw. Theory Tech., Vol. 60, 484-493, 2012.
doi:10.1109/TMTT.2011.2181533
8. Chao, S.-F., W.-C. Lin, and C.-Y. Kuo, "Bandpass filter with tunable bandwidth using triple-mode H-type resonator," International Symposium on Next-Generation Electronics, 1-3, 2014.
9. Huang, X.-G., Q.-Y. Feng, and Q.-Y. Xiang, "Bandpass filter with tunable bandwidth using quadruple-mode stub-loaded resonator," IEEE Microw. Wireless Compon. Lett., Vol. 22, 176-178, 2012.
doi:10.1109/LMWC.2012.2188280
10. Mao, J.-R., W.-W. Choi, K.-W. Tam, W.-Q. Che, and Q. Xue, "Tunable bandpass filter design based on external quality factor tuning and multiple mode resonators for wideband applications," IEEE Trans. Microw. Theory Tech., Vol. 61, 2574-2584, 2013.
doi:10.1109/TMTT.2013.2264684
11. Li, Y. C. and Q. Xue, "Tunable balanced bandpass filter with constant bandwidth and high common-mode suppression," IEEE Trans. Microw. Theory Tech., Vol. 59, 2452-2460, 2011.
doi:10.1109/TMTT.2011.2161325
12. Mao, J.-R., W.-Q. Che, Y.-L. Ma, and J.-X. Chen, "Tunable differential-mode bandpass filters withwide tuning range and high common-mode suppression," IET Microw. Antennas Propag., Vol. 8, 437-444, 2014.
doi:10.1049/iet-map.2012.0203
13. Chun, Y.-H. and J.-S. Hong, "Electronically reconfigurable dual-mode microstrip open-loop resonator filter," IEEE Microw. Wireless Compon. Lett., Vol. 7, 449-451, 2008.
doi:10.1109/LMWC.2008.924922
14. Pozar, D. M., Microwave Engineering, Wiley, New York, 1998.
Submit
