PIER Letters
Progress In Electromagnetics Research Letters
ISSN: 1937-6480
Home | Search | Notification | Authors | Submission | PIERS Home | EM Academy
Home > Vol. 49 > pp. 79-85


By L. Yang and W. Feng

Full Article PDF (1,245 KB)

A novel wideband balun filter based on a symmetric four-port balanced circuit is proposed in this paper. A pair of open coupled lines is used to realize DC suppression and in-band balance improvement for the balun bandpass filter. The bandwidth can be easily adjusted by changing the characteristic impedance of transmission lines in the balanced circuit. For the proposed balun bandpass filter, excellent in-band balance performance (amplitude and phase imbalance are less than 0.25 dB and 1.3˚ respectively) over the passband are achieved. A wideband balun bandpass filter prototype with center frequency 3.75 GHz and 3-dB bandwidth 33.8% is designed and fabricated. Good agreement can be observed between the measured results and theoretical expectations.

L. Yang and W. Feng, "Wideband Balun Bandpass Filter Based on a Balanced Circuit," Progress In Electromagnetics Research Letters, Vol. 49, 79-85, 2014.

1. Jung, E.-Y. and H.-Y. Hwang, "A balun-BPF using a dual mode ring resonator," IEEE Microw. Wireless Compon. Lett., Vol. 17, 652-654, 2007.

2. 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, 2001.

3. Ang, K. S., Y. C. Leong, and C. H. Lee, "Analysis and design of miniaturized lumped-distributed impedance-transforming baluns," IEEE Trans. Microw. Theory Techn., Vol. 51, 1009-1017, 2003.

4. Ang, K. S. and I. D. Robertson, "Analysis and design of impedance-transforming planar Marchand baluns," IEEE Trans. Microw. Theory Techn., Vol. 49, 402-406, 2001.

5. Zhang, Z.-Y., Y.-X. Guo, L. C. Ong, and M. Y. W. Chia, "A new wide-band planar balun on a single-layer PCB," IEEE Microw. Wireless Compon. Lett., Vol. 15, 416-418, 2005.

6. Wu, C. H., C. H. Wang, S. Y. Chen, and C. H. Chen, "Balanced-to unbalanced bandpass filters and the antenna application," IEEE Trans. Microw. Theory Techn., Vol. 56, 2474-2482, 2008.

7. Yang, T., M. Tamura, and T. Itoh, "Compact hybrid resonator with series and shunt resonances used in miniaturized filters and balun filters," IEEE Trans. Microw. Theory Techn., Vol. 58, 390-402, 2010.

8. Xue, Q., J. Shi, and J. X. Chen, "Unbalanced-to-balanced and balanced-to-unbalanced diplexer with high selectivity and common-mode suppression," IEEE Trans. Microw. Theory Techn., Vol. 58, 970-977, 2010.

9. Eisenstant, W. R., B. Stengel, and B. M. Thompson, Microwave Differential Circuit Design Using Mixed-mode S-parameters, Artech House, Boston, MA, 2006.

10. Leong, Y. C., K. S. Ang, and C. H. Lee, "A derivation of a class of 3-port baluns form symmetrical 4-port networks," IEEE MTT-S Int. Microw. Symp. Dig., 1165-1168, 2002.

11. 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 Electromagnetic Research Letter, Vol. 40, 39-48, 2013.

12. Feng, W. J., W. Q. Che, L. M. Gu, and Q. Xue, "High selectivity wideband balanced bandpass filters using symmetrical multi-mode resonators," IET Microw. Antennas Propag., Vol. 7, 1005-1015, 2013.

© Copyright 2010 EMW Publishing. All Rights Reserved