A novel compact wideband differential bandpass filter with wideband common mode suppression using a Marchand balun is presented in this paper. Open/shorted coupled lines and stubs are used to improve the selectivity for the differential mode and common mode suppression. The demonstrated filter with a compact size of 50 mm × 30 mm exhibits a fractional bandwidth of 53% centered at 3.0 GHz and 13 dB common-mode suppression from 0 to 9 GHz. The theoretical and measured results agree well with each other and show good in-band performances.
2. 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 Techn., Vol. 55, No. 2, 287-295, 2007.
3. 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.
4. Shi, J. and Q. Xue, "Balanced bandpass filters using center-loaded half-wavelength resonators," IEEE Trans. Microw. Theory Techn., Vol. 58, No. 4, 970-977, 2010.
5. 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 Letters, Vol. 121, 365-379, 2011.
6. Wu, S. M., C. T. Kuo, and C. H. Chen, "Very compact full differ-ential bandpass filter with transformer integrated using integrated passive device technology," Progress In Electromagnetics Research Letters, Vol. 113, 251-267, 2011.
7. Lim, S. C., C. Y, and Yeh, "Stopband-extended 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.
8. Lim, T. B. and L. Zhu, "Highly selective differential-mode wideband bandpass filter for UWB application," IEEE Microw. Wireless Compon. Lett., Vol. 21, 133-135, 2011.
9. Feng, W. J., W. Q. Che, Y. L. Ma, and Q. Xue, "Compact wideband differential bandpass filter using half-wavelength ring resonator," IEEE Microw. Wireless Compon. Lett., Vol. 23, 81-83, 2013.
10. Wang, X. H., Q. Xue, and W. W. Choi, "A novel ultra-wideband differential filter based on doublesided parallel-strip line," IEEE Microw. Wireless Compon. Lett., Vol. 20, 471-473, 2010.
11. Feng, W. J., W. Q. Che, T. F. Eibert, and Q. Xue, "Compact wideband differential bandpass filter based on the double-sided parallel-strip line and transversal signal-interaction concepts," IET Microw. Antennas Propag., Vol. 6, No. 2, 186-195, 2012.
12. Lu, Y. J., S. Y. Chen, and P. Hsu, "A differential-mode wideband bandpass filter with enhanced common-mode suppression using slotline resonator," IEEE Microw. Wireless Compon. Lett., Vol. 22, 503-505, 2012.
13. 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, 1034-1035, 2011.
14. Feng, W. J. and W. Q. Che, "Novel wideband differential bandpass filter based on T-shaped structure," IEEE Trans. Microw. Theory Techn., Vol. 60, 1560-1568, 2012.
15. 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 Letter, Vol. 40, 39-48, 2013.
16. Matthaei, G., L. Young, and E. M. T. Jones, Microwave Filters, Impedance Matching Networks and Coupling Structures, Artech House Inc., Norwood, MA, 1985.
17. Guo, Y. X., Z. Y. Zhang, and L. C. Ong, "Improved wide-band schiffman phase shifter," IEEE Trans. Microw. Theory Techn., Vol. 54, No. 3, 2412-2418, 2006.