volume | PIER Journals

Abstract

Compact symmetrical four-ports differential bandpass filters with good common-mode suppressions are proposed in this work. The presented filters are designed based on half-wavelength coupled resonators with compact size, good filtering responses for differential-mode, and wide common-mode suppression range. To further improve the common-mode performances within the differential-mode passband, T-shaped resonators are loaded at the center of the structure. It is noted that, the size of filter does not become larger with loaded T-shaped resonators. Both these two filters are centered at 1.8 GHz for Global System Mobile Communication (GSM) with 7.8% fractional bandwidth. For differential-mode, the insertion is less than -1.2 dB in the 3-dB passband and the matching is better than -20 dB. Good stopband characteristics are also obtained with more than -20 dB out-of-band attenuation from dc to 1.6 GHz in the lower stopband and from 2.0 to 4.8 GHz in the upper stopband. For common-mode, better than -15 dB suppression is achieved within dc to 6.2 GHz and with the help of the loaded T-shaped resonators, the rejection in the differential-mode passband is improved to be more than -40 dB. Theory analysis, simulation, and measurement show good agreement with each other.

1. Wu, X. H. and Q. X. Chu, "Compact differential ultra-wideband bandpass filter with common-mode suppression," IEEE Microw. Wireless Compon. Lett., Vol. 2, No. 9, 456-458, 2012. Google Scholar

2. Lim, T. B. and L. Zhu, "Highly selective differential-mode wideband bandpass filter for UWB application," IEEE Microw. Wireless Compon. Lett., Vol. 21, No. 3, 133-135, 2011. Google Scholar

3. Lim, T. B. and L. Zhu, "A differential-mode wideband bandpass filter on microstrip line for UWB application," IEEE Microw. Wireless Compon. Lett., Vol. 19, No. 10, 632-634, 2009. Google Scholar

4. Feng, W. J., W. Q. Che, Y. L. Ma, and Q. Xue, "Compact wideband differential bandpass filters using half-wavelength ring," IEEE Microw. Wireless Compon. Lett., Vol. 23, No. 2, 81-83, 2013. Google Scholar

5. 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, 2011. Google Scholar

6. Wang, H., W. Kang, G. Yang, and W. Wu, "A wideband differential bandpass filter based on T-shaped stubs and single ring resonator," Progress In Electromagnetics Research Letters, Vol. 40, 39-48, 2013. Google Scholar

7. Zhu, H. T., W. J. Feng, W. Q. Che, and Q. Xue, "Ultra-wideband differential bandpass filter based on transversal signal-interference concept," Electron. Lett., Vol. 47, No. 18, 1033-1035, 2011. Google Scholar

8. Shi, W. W. Choi, W. Q. Che, K. W. Tam, and Q. Xue, "Ultra-wideband differential bandpass filter with narrow notched band and improved common-mode suppression by DGS," IEEE Microw. Wireless Compon. Lett., Vol. 22, No. 4, 185-187, 2012. Google Scholar

9. 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. Google Scholar

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

11. Wu, C. H., C. H. Wang, and C. H. Chen, "Balanced coupled-resonator bandpass filters using multisection resonators for ommon-mode suppression and stopband extension," IEEE Trans. Microwave Theory & Tech., Vol. 55, No. 8, 17561763, 2007. Google Scholar

12. Wu, C. H., C. H.Wang, and C. H. Chen, "Novel balanced coupled-line bandpass filters with common-mode noise suppression," IEEE Trans. Microwave Theory & Tech., Vol. 55, No. 2, 287-295, 2007. Google Scholar

13. Shi, J. and Q. Xue, "Balanced bandpass filters using center-loaded half-wavelength resonators," IEEE Trans. Microwave Theory & Tech., Vol. 58, No. 4, 970-977, 2010. Google Scholar

14. Niu, J. X. and X. L. Zhou, "Analysis of balanced composite right/left handed structure based on different dimensions of complementary split ring resonators," Progress In Electromagnetics Research, Vol. 74, 341-351, 2007. Google Scholar

15. Kim, Y. and S. Sim, "Symmetric coupled composite right-/left-handed transmission line in common-/differential-mode operation," Progress In Electromagnetics Research Letters, Vol. 40, 1-8, 2013. Google Scholar

16. Lee, C. H., C. I. G. Hsu, and C. J. Chen, "Band-notched balanced UWB BPF with stepped-impedance slotline multi-mode resonator," IEEE Microw. Wireless Compon. Lett., Vol. 22, No. 4, 182-184, 2012. Google Scholar

17. Shi, J. and Q. Xue, "Novel balanced dual-band bandpass filter using coupled stepped-impedance resonators," IEEE Microw. Wireless Compon. Lett., Vol. 20, No. 1, 19-21, 2010. Google Scholar

18. Lin, S. C., C. Y, and Yeh, "Stopband-extenede balanced filters using both λ/4 and λ/2 SIRs with common-mode suppression and improved passband selectivity," Progress In Electromagnetics Research, Vol. 128, 215-228, 2012. Google Scholar

19. Cho, Y. H. and S. W. Yun, "Design of balanced dual-band bandpass filters using asymmetrical coupled lines," IEEE Trans. Microwave Theory & Tech., Vol. 61, No. 8, 2814-2820, 2013. Google Scholar

20. Lee, C. H., C. I. G. Hsu, and C. C. Hsu, "Balanced dual-band BPF with stub-loaded SIRs for common-mode suppression," IEEE Microw. Wireless Compon. Lett., Vol. 20, No. 2, 70-72, 2010. Google Scholar

21. Wang, X. H., H. L. Zhang, and B. Z. Wang, "A novel ultra-wideband differential filter based on microstrip line structures," IEEE Microw. Wireless Compon. Lett., Vol. 23, No. 3, 128-130, 2013. Google Scholar

22. Wang, X. H., Q. Xue, and W. W. Choi, "A novel ultra-wideband differential filter based on double-sided parallel-strip line," IEEE Microw. Wireless Compon. Lett., Vol. 20, No. 8, 471-473, 2010. Google Scholar

23. Xia, B., L. S. Wu, and J. F. Mao, "An ultra-wideband balanced bandpass filter based on defected ground structures," Progress In Electromagnetics Research C, Vol. 25, 133-144, 2012. Google Scholar

24. Fernandez-Prieto, A., J. Martel, F. Medina, F. Mesa, S. Qian, J. S. Hong, J. Naqui, and F. Martin, "Dual-band differential filter using broadband common-mode rejection artificial transmission line," Progress In Electromagnetics Research, Vol. 139, 779-797, 2013. Google Scholar

25. Reed, J. and G. J. Wheeler, "A method of analysis of symmetrical four-port networks," IRE Trans. Microwave Theory & Tech., Vol. 4, No. 4, 246-252, 1956. Google Scholar

Dr. Hui Wang

Dr. Xuan Li

Dr. Wei Kang

Dr. Chen Tan

Dr. Wen Wu

Dr. Guo Yang