volume | PIER Journals

Abstract

In this paper, a novel end-loaded quarter-wavelength resonator is investigated for the designs of wideband tunable bandpass filter (BPF) and bandstop filter (BSF). The novelty of the resonator lies in that two varactors are added to the two ends of the resonator, and then its resonant frequency can be bi-directionally tuned. As a result, the theoretical frequency tuning range can be significantly extended to approximately double that of the conventional tunable quarter-wavelength resonator. For demonstration, the proposed resonator is applied to design wideband tunable BPF and BSF. As expected, the tuning ranges are 52.4% and 53.5% for the BSF and BPF, respectively. Good agreement can be observed between the simulated and measured results.

1. Li, L. and D. Uttamchandani, "Demonstration of a tunable RF MEMS bandpass filter using silicon foundry process," Journal of Electromagnetic Waves and Applications, Vol. 23, No. 23, 405-413, 2009.
doi:10.1163/156939309787604355

2. Saha, S. C., U. Hanke, H. Sagberg, T. A. Fjeldly, and T. Saether, "Tunable bandpass filter using RF MEMS capacitance and transmission line," Progress In Electromagnetics Research C, Vol. 23, 2011.

3. Shalaby, M. M., Z.Wang, L.-W. Chow, B. D. Jensen, J. L. Volakis, K. Kurabayashi, and K. Saitou, "Robust design of RF-MEMS cantilever switches using contact physics modeling," IEEE Trans. Indus. Electron., Vol. 56, No. 4, 1012-1020, 2009.
doi:10.1109/TIE.2008.2006832

4. Reines, I., S. J. Park, and G. M. Rebeiz, "Compact low-loss tunable X-band bandstop filter with miniature RF-MEMS switches," IEEE Trans. Microw. Theory and Tech., Vol. 58, No. 7, 1887-1895, 2010.
doi:10.1109/TMTT.2010.2050621

5. Janardhana, V., S. Pamidighantam, N. Chattoraj, and R. G. Kulkarni, "Experimental investigations on a surface micro-machined tunable lowpass filter," Progress In Electromagnetics Research Letters, Vol. 27, 171-178, 2011.
doi:10.2528/PIERL11081803

6. Jung, D.-J. and K. Chang, "Accurate modeling of microstrip dumbbell shaped slot resonator (DSSR) for miniaturized tunable resonator and band-pass filter," Progress In Electromagnetics Research C, Vol. 23, 137-150, 2011.
doi:10.2528/PIERC11071705

7. Yu, F. L., X. Y. Zhang, and Y. B. Zhang, "Frequency-tunable bandpass filters with constant absolute bandwidth and improved linearity," Progress In Electromagnetics Research Letters, Vol. 33, 131-140, 2012.

8. Wang, Y.-Y., F. Wei, B. Liu, H. Xu, and X.-W. Shi, "A tunable bandpass filter with constant absolute bandwidth based on one ring resonator," Journal of Electromagnetic Waves and Applications, Vol. 26, No. 11-12, 1587-1593, 2012.
doi:10.1080/09205071.2012.705137

9. Wei, F., L. Chen, X.-W. Shi, and C.-J. Gao, "UWB bandpass filter with one tunable notch-band based on DGS," Journal of Electromagnetic Waves and Applications, Vol. 26, No. 5-6, 673-680, 2012.
doi:10.1080/09205071.2012.710788

10. Liu, B., F. Wei, Q. Y. Wu, and X. W. Shi, "A tunable bandpass filter with constant absolute bandwidth," Journal of Electromagnetic Waves and Applications, Vol. 25, No. 11-12, 1596-1604, 2011.
doi:10.1163/156939311797164819

11. Wang, S. and R. X. Wang, "A tunable bandpass fillter using Q-enhanced and semi-passive inductors at S-band in 0.18 CMOS," Progress In Electromagnetics Research B, Vol. 28, 55-73, 2011.

12. Sanchez-Renedo, M., "High-selectivity tunable planar combline filter with source/load multiresonator coupling," IEEE Microw. and Wirel. Compon. Lett., Vol. 7, No. 7, 513-515, 2007.
doi:10.1109/LMWC.2007.899313

13. Kim, B. W. and S. W. Yun, "Varactor-tuned combline bandpass filter using step impedance microstrip lines," IEEE Trans. Microw. Theory and Tech., Vol. 52, No. 4, 1279-1283, 2004.
doi:10.1109/TMTT.2004.825626

14. Brown, A. R. and G. M. Rebeiz, "A varactor-tuned RF filter," IEEE Trans. Microw. Theory and Tech., Vol. 9, No. 7, 1157-1160, 2000.
doi:10.1109/22.848501

15. Hunter, I. C. and J. D. Rhodes, "Electronically tunable microwave bandstop filters," IEEE Trans. Microw. Theory and Tech., Vol. 30, No. 9, 1361-1367, 1982.
doi:10.1109/TMTT.1982.1131261

16. Wang, X. H., B.-Z. Wang, H. L. Zhang, and K. J. Chen, "A tunable bandstop resonator based on a compact slotted ground structure," IEEE Trans. Microw. Theory and Tech., Vol. 55, No. 9, 1912-1918, 2007.
doi:10.1109/TMTT.2007.904045

17. Zhang, X. Y., C. H. Chan, Q. Xue, and B. J. Hu, "RF tunable bandstop filters with constant bandwidth based on a doublet configuration," IEEE Trans. Indus. Electron., Vol. 59, No. 2, 1257-1265, 2012.
doi:10.1109/TIE.2011.2158038

18. Chun, Y. H., J. S. Hong, P. Bao, T. J. Jackson, and M. J. Lancaster, "Tunable slotted ground structured bandstop filter with BST varactors," IET Microw. Antennas Propag., Vol. 3, No. 5, 870-876, 2009.
doi:10.1049/iet-map.2008.0308

19. Tsai, C. S., "Tunable wideband microwave bandstop and bandpass filters using YIG/GGG-GaAs layer structures," IEEE Trans. Magnetics, Vol. 41, No. 10, 3568-3570, 2005.
doi:10.1109/TMAG.2005.855191

20. Matthaei, G. L., "Combline band-pass filters of narrow or moderate bandwidth," Microwave J., 82-91, 1963.

21. Hong, J. S. and M. J. Lancaster, Microstrip Filter for RF/Microwave Applications, Wiley, New York, 2001.

22. Chen, J. X., J. Shi, Z. H. Bao, and Q. Xue, "Tunable and switchable bandpass filters using slot-line resonators," Progress In Electromagnetics Research, Vol. 111, 25-41, 2011.
doi:10.2528/PIER10100808

Dr. Ya-Lin Ma

Prof. Wenquan Che

Prof. Jian-Xin Chen

Dr. Jinrong Mao