volume | PIER Journals

Abstract

Benefitting from the simultaneous utilization of quarter-wave (λ/4) and half-wave (λ/2) microstrip resonators, a via-free balanced bandpass filter (BPF) with direct-coupled scheme is presented in this study. In the beginning, a single-ended filter with transmission zeros (TZs) is newly proposed and the mechanism of creating two TZs around the passband without necessitating cross couplings is adopted. The TZs can be made structure-inherent based on the coexisted out-of-phase couplings among a coupled-resonator pair. On the foundation of the presented single-ended filter, a balanced filter featuring extended differential-mode (DM) stopband, good common-mode (CM) suppression, and improved passband selectivity has been designed and implemented. The DM stopband extension is achieved by misaligning the higher-order harmonic frequencies of each resonator in the DM bisected circuit while the CM suppression is accomplished by both harmonic misalignment and careful designed coupled structure in the CM bisected circuit. Eventually, a demonstrated balanced filter centering at 1.5 GHz possesses DM stopband extended up to 8f^d₀, where f^d₀ denotes the DM operation frequency, and its CM rejection ratio (CMRR) within DM passband better than 51.9 dB is attained. For measurement convenience, the DM characterizations have been accomplished by 2-port network analyzer with simple rat-race baluns and are found relatively accurate within the -15dB bandwidth of the utilized baluns.

1. Bockelman, D. E. and W. R. Eisenstant, "Combined differential and common-mode scattering parameters: Theory and simulation," IEEE Trans. Microw. Theory Tech., Vol. 43, No. 7, 1530-1539, Jul. 1995.
doi:10.1109/22.392911

2. Wang, F. J. and J. S. Zhang, "Wideband printed dipole antenna for multiple wireless services," Journal of Electromagnetic Waves and Applications, Vol. 21, No. 11, 1469-1477, 2007.
doi:10.1163/156939307782000389

3. Kuo, F. Y. and H. T. Hsu, "Omni-directional dipole-based wideband planar antenna with capacitive end loading for WiMAX applications," Journal of Electromagnetic Waves and Applications, Vol. 24, No. 7, 959-969, 2010.
doi:10.1163/156939310791285263

4. Guo, J., Z. Xu, C. Qian, and W.-B. Dou, "Design of a microstrip balanced mixer for satellite communication," Progress In Electromagnetics Research, Vol. 115, 289-301, 2011.

5. Lee, Y.-C., C.-M. Lin, S.-H. Hung, C.-C. Su, and Y.-H. Wang, "A broadband doubly balanced monolithic ring mixer with a compact intermediate frequency (IF) extraction," Progress In Electromagnetics Research Letters, Vol. 20, 175-184, 2011.

6. Lee, Y.-C., Y.-H. Chang, S.-H. Hung, W.-C. Chien, C.-C. Su,C.-C. Hung, C.-M. Lin, and Y.-H. Wang, "A single-balanced quadruple subharmonical mixer with a compact IF extraction," Progress In Electromagnetics Research Letters, Vol. 24, 159-167, 2011.

7. Lin, Y.-S. and C. H. Chen, "Novel balanced microstrip coupled-line bandpass filters," Proc. URSI Int. Electromagn. Theory Symp., 567-569, 2004.

8. Wu, C.-H., C.-H.Wang, and C. H. Chen, "Novel balanced coupled-line bandpass filters with common-mode noise suppression," IEEE Trans. Microw. Theory Tech., Vol. 55, No. 2, 287-295, Feb.2007.
doi:10.1109/TMTT.2006.889147

9. Shi, J., J.-X. Chen, and Q. Xue, "A novel differential bandpass filter based on double-sided parallel-strip line dual-mode resonator," Microw. Opt. Tech. Lett., Vol. 50, No. 7, 1733-1735, Jul.2008.
doi:10.1002/mop.23493

10. Wu, C.-H., C.-H. Wang, and C. H. Chen, "Balanced coupled-resonator bandpass filters using multisection resonators for common-mode suppression and stopband extension," IEEE Trans. Microw. Theory Tech., Vol. 55, No. 8, 1756-1756, Aug. 2007.
doi:10.1109/TMTT.2007.901609

11. Lee, C.-H., I.-C. Wang, and C.-I. G. Hsu, "Dual-band balanced BPF using λ/4 stepped-impedance resonators and folded feed lines," Journal of Electromagnetic Wave and Applications, Vol. 23, No. 17-18, 2441-2449, 2009.

12. Hsu, C. I. G., C.-C. Hsu, C.-H. Lee, and H.-H. Chen, "Balanced dual-band BPF using only equal-electric-length SIRs for common-mode suppression," Journal of Electromagnetic Waves and Applications, Vol. 24, No. 5-6, 695-705, 2010.
doi:10.1163/156939310791036241

13. Lee, C.-H., C.-I. G. Hsu, H.-H. Chen, and Y.-S. Lin, "Balanced single- and dual-band BPFs using ring resonators," Progress In Electromagnetics Research, Vol. 116, 333-346, 2010.

14. Wu, S.-M., C.-T. Kuo, P.-Y. Lyu, Y.-L. Shen, and C.-I. Chien, "Miniaturization design of full differential bandpass filter with coupled resonators using embedded passive device technology," Progress In Electromagnetics Research, Vol. 121, 365-379, 2011.
doi:10.2528/PIER11091404

15. Wu, S.-M., C.-T. Kuo, and C.-H. Chen, "Very compact full differential bandpass filter with transformer integrated using inte-grated passive device technology," Progress In Electromagnetics Research, Vol. 113, 251-267, 2011.

16. Kuo, J.-T. and E. Shih, "Microstrip stepped impedance resonator bandpass filter with an extended optimal rejection bandwidth," IEEE Trans. Microw. Theory Tech., Vol. 51, No. 5, 1554-1559, May 2003.
doi:10.1109/TMTT.2003.810138

17. Yang, R.-Y., C.-Y. Hung, and J.-S. Lin, "Design and fabrication of a quad-band bandpass filter using multi-layered sir structure," Progress In Electromagnetics Research, Vol. 114, 457-468, 2011.

18. Lin, S.-C., C.-H. Wang, and C. H. Chen, "Novel patch-via-spiral resonators for the development of miniaturized bandpass filters with transmission zeros," IEEE Trans. Microw. Theory Tech., Vol. 55, No. 1, 137-146, Jan. 2007.
doi:10.1109/TMTT.2006.888579

19. Lin, S. C., P. H. Deng, Y. S. Lin, C. H. Wang, and C. H. Chen, "Wide-stopband microstrip bandpass filters using dissimilar quarter-wavelength stepped-impedance resonators," IEEE Trans. Microw. Theory Tech., Vol. 54, No. 3, 1011-1018, Mar. 2006.
doi:10.1109/TMTT.2005.864139

20. Wu, H.-W., S.-K. Liu, M.-H. Weng, and C.-H. Hung, "Compact microstrip bandpass filter with multispurious suppression," Progress In Electromagnetics Research, Vol. 107, 21-30, 2010.
doi:10.2528/PIER10061601

21. Bockelman, D. E. and W. R. Eisenstant, "Pure-mode network analyzer for on-wafer measurements of mixed-mode S-parameters of differential circuits," IEEE Trans. Microw. Theory Tech., Vol. 45, No. 7, 1071-1077, Jul. 1997.
doi:10.1109/22.598443

22. Pozar, D. M., Microwave Engineering, 3rd Edition, Wiley, New York, 2011.

23. Shao, W. and J.-L. Li, "A compact log-periodic branch-line balun with an octave bandwidth," Journal of Electromagnetic Waves and Applications, Vol. 25, No. 14-15, 2033-2042, 2011.
doi:10.1163/156939311798072108

Dr. Shih-Cheng Lin

Dr. Chong-You Yeh