volume | PIER Journals

Abstract

new circuit structure is proposed for design of dual-band bandpass filters with a wide upper stopband. The unit cell of the circuit consists of two two-port networks in shunt connection; one is a coupled-line section of λ/4 long followed by a transmission line segment of identical length, and the other has the same elements but cascaded in reverse order, where λ/4 is the wavelength at arithmetic mean frequency of the two passbands. Higher-order circuits can be obtained by directly cascading two or more such cells and show improved frequency selectivity. In addition to on both sides of the passbands, transmission zeros are also created in the rejection bands. Analysis of the unit cell circuit is formulated by the transmission line theory, and design curves for one- and two-cell circuits are provided. In realization, interdigital capacitors are incorporated with the λ/4 coupled sections for compensating the effect of unequal modal phase velocities on the filter performance in the rejection band. Two circuits are fabricated and measured to validate the analysis.

1. Kuo, J.-T. and H.-S. Cheng, "Design of quasi-elliptic function filters with a dual-passband response," IEEE Microwave Wireless Compon. Lett., Vol. 14, No. 10, 472-474, Oct. 2004.
doi:10.1109/LMWC.2004.834560

2. Kuo, J.-T., T.-H. Yeh, and C.-C. Yeh, "Design of microstrip bandpass filters with a dual-passband response," IEEE Trans. Microwave Theory Tech., Vol. 53, No. 11, 1331-1337, Apr. 2005.

3. Kuo, J.-T. and H.-P. Lin, "Dual-band bandpass filter with improved performance in extended upper rejection band," IEEE Trans. Microwave Theory Tech., Vol. 57, No. 4, 824-829, Apr. 2009.
doi:10.1109/TMTT.2009.2015040

4. Mondal, P. and M. K. Mondal, "Design of dual-band bandpass filters using stub-loaded open-loop resonators," IEEE Trans. Microwave Theory Tech., Vol. 56, No. 1, 150-154, Jan. 2008.
doi:10.1109/TMTT.2007.912204

5. Ma, D., Z. Y. Xiao, L. Xiang, X. Wu, C. Huang, and X. Kou, "Compact dual-band bandpass filter using folded SIR with two stubs for WLAN," Progress In Electromagnetics Research, Vol. 117, 357-364, 2011.

6. Chen, C.-Y. and C.-C. Lin, "The design and fabrication of a highly compact microstrip dual-band bandpass filter," Progress In Electromagnetics Research, Vol. 112, 299-307, 2011.

7. Chen, C.-H., C.-S. Shih, T.-S. Horng, and S.-M. Wu, "Very miniature dual-band and dual-mode bandpass filter designs on an integrated passive device chip," Progress In Electromagnetics Research, Vol. 119, 461-476, 2011.
doi:10.2528/PIER11080105

8. Chiou, Y.-C., C.-Y. Wu, and J.-T. Kuo, "New miniaturized dual-mode dual-band ring resonator bandpass filter with microwave C-sections," IEEE Microwave Wireless Compon. Lett., Vol. 20, No. 2, 67-69, Feb. 2010.
doi:10.1109/LMWC.2009.2038432

9. Lugo, C. and J. Papapolymerou, "Multilayer dual-band filter using a reflector cavity and dual-mode resonators," IEEE Microwave Wireless Compon. Lett., Vol. 17, No. 9, 637-639, Sep. 2007.
doi:10.1109/LMWC.2007.903435

10. Lin, T.-W., U-H. Lok, and J.-T. Kuo, "New dual-mode dual-band bandpass filter with quasi-elliptic function passbands and controllable bandwidths," IEEE MTT-S Int. Dig., 576-579, Jun. 2010.

11. Yang, R.-Y., H. Kuan, C.-Y. Hung, and C.-S. Ye, "Design of dual-band bandpass filters using a dual feeding structure and embedded uniform impedance resonators," Progress In Electromagnetics Research, Vol. 105, 93-102, 2010.
doi:10.2528/PIER10042504

12. Tsai, C.-M., H.-M. Lee, and C.-C. Tsai, "Planar filter design with fully controllable second passband," IEEE Trans. Microwave Theory Tech., Vol. 53, No. 11, 3429-3439, Nov. 2005.
doi:10.1109/TMTT.2005.855739

13. Lee, H.-M. and C.-M. Tsai, "Dual-band filter design with flexible passband and bandwidth selections," IEEE Trans. Microwave Theory Tech., Vol. 55, No. 5, 1002-1009, May 2007.
doi:10.1109/TMTT.2007.895410

14. Liu, A.-S., T.-Y. Huang, and R.-B. Wu, "A dual wideband filter design using frequency mapping and stepped-impedance resonators," IEEE Trans. Microwave Theory Tech., Vol. 56, No. 12, 2921-2929, Dec. 2008.
doi:10.1109/TMTT.2008.2007357

15. Guan, X., Z. Ma, P. Cai, Y. Kobayashi, T. Anada, and G. Hagiwara, "Synthesis of dual-band bandpass filters using successive frequency transformations and circuit conversions," IEEE Microwave Wireless Compon. Lett., Vol. 16, No. 3, 110-112, Mar. 2006.
doi:10.1109/LMWC.2006.869868

16. Lai, S.-W., New dual-band bandpass filter with desired rejection response, M.S. Thesis, National Chiao Tung University, Hsinchu, Taiwan, Jun. 2010.

17. Chin, K.-S. and J.-T. Kuo, "Insertion loss function synthesis of maximally flat parallel-coupled line bandpass filters," IEEE Trans. Microwave Theory Tech., Vol. 53, No. 10, 3161-3168, Oct. 2005.
doi:10.1109/TMTT.2005.855355

18. Kuo, J.-T., S.-P. Chen, and M. Jiang, "Parallel-coupled microstrip filters with over-coupled end stages for suppression of spurious responses," IEEE Microwave Wireless Compon. Lett., Vol. 13, No. 10, 440-442, Oct. 2003.

19. Press, W. H., S. A. Teukolsky, W. T. Vetterling, and B. P. Flannery, Numerical Recipes in FORTRAN 77, 2nd Ed., Cambridge University Press, 1992.

20. IE3D simulator, Zeland Software Inc., Jan. 2002.

21. Dydyk, M., "Accurate design of microstrip directional couplers with capacitive compensation," IEEE MTT-S Int. Dig., 581-584, 1990.

22. Alley, G. D., "Interdigital capacitors and their application to lumped-element microwave integrated circuits," IEEE Trans. Microwave Theory Tech., Vol. 18, No. 12, 1028-1033, Dec. 1970.
doi:10.1109/TMTT.1970.1127407

Prof. Jen-Tsai Kuo

Dr. Shih-Wei Lai