In this paper, a wideband differential phase shifter based on modified T- and Pi- networks is proposed. Invoking the even-odd mode analysis in this symmetric phase shifter, closed-form equations of its S-parameters are derived. The derived equations enable a generic design scheme of the phase shifter, that is, ideally the phase shifter can be designed for any differential phase requirements. To illustrate the proposed idea, design parameters for differential phases of 45˚, 60˚, 75˚, 90˚, 105˚ and 120˚ are evaluated and tabulated considering a center frequency of 3 GHz. Simulation of these examples using the Keysight ADS exhibits the intended performance. For validation, a 90˚ phase shifter has been fabricated and tested. The measurement results show a return loss better that 10 dB, an insertion loss of less than 1 dB, and a ± 7° of phase deviation from 1.18 GHz to 5.44 GHz, which is equivalent to a fractional bandwidth of 142%.
2. Schiek, B. and J. Kohler, "A method for broad-band matching of microstrip differential phase shifters," IEEE Transactions on Microwave Theory and Techniques, Vol. 25, No. 8, 666-671, August 1977.
3. Brown, W. J. and J. P. Starski, "A broad-band differential phase shifter of novel design," IEEE MTT-S International Microwave Symposium Digest, Vol. 3, 1319-1322, 1999.
4. Quirarte, J. L. R. and J. P. Starski, "Novel Schiffman phase shifters," IEEE Transactions on Microwave Theory and Techniques, Vol. 41, No. 1, 9-14, January 1993.
5. Guo, Y., Z. Zhang, and L. Ong, "Improved wideband Schiffman phase shifter," IEEE Transactions on Microwave Theory and Techniques, Vol. 54, No. 3, 1196-1200, March 2006.
6. Abbosh, A. M., "Ultra-wideband phase shifters," IEEE Transactions on Microwave Theory and Techniques, Vol. 55, No. 9, 1935-1941, September 2007.
7. Guo, L. and A. M. Abbosh, "Phase shifters with wide range of phase and ultra-wideband performance using stub-loaded coupled structure," IEEE Microwave and Wireless Components Letters, Vol. 24, No. 3, 167-169, March 2014.
8. Zheng, S. Y., W. S. Chan, and K. F. Man, "Broadband phase shifter using loaded transmission line," IEEE Microwave and Wireless Components Letters, Vol. 20, No. 9, 498-500, September 2010.
9. Tang, X. and K. Mouthaan, "Design of a UWB phase shifter using shunt λ/4 stubs," IEEE MTT-S International Microwave Symposium Digest, 1021-1024, June 2009.
10. Yeung, S. H., Z. Mei, T. K. Sarkar, and M. Salazar-Palma, "Design and testing of a single-layer microstrip ultrawideband 90 differential phase shifter," IEEE Microwave and Wireless Components Letters, Vol. 23, No. 3, 122-124, March 2013.
11. Wang, J., Z. Shen, and L. Zhao, "UWB 90º phase shifter based on broadside coupler and T-shaped stub," IET Electronics Letters, Vol. 52, No. 25, 2048-2050, December 2016.
12. Abbosh, A. M., "Broadband fixed phase shifters," IEEE Microwave and Wireless Components Letters, Vol. 21, No. 1, 22-24, January 2011.
13. Pu, X. Y., S. Y. Zheng, J. Liu, Y. Li, and Y. Long, "Novel multi-way broadband differential phase shifter with uniform reference line using coupled line structure," IEEE Microwave and Wireless Components Letters, Vol. 25, No. 3, 166-168, March 2015.
14. Xu, B. W., S. Y. Zheng, and Y. M. Pan, "A universal reference line-based differential phase shifter structure with simple design formulas," IEEE Transactions on Components, Packaging and Manufacturing Technology, Vol. 7, No. 1, 123-130, January 2017.
15. Wang, Y., M. E. Bialkowski, and A. M. Abbosh, "Double microstrip-slot transitions for broadband microstrip phase shifters," IEEE Microwave and Wireless Components Letters, Vol. 22, No. 2, 58-60, February 2012.
16. Zhang, W., Y. Liu, Y. Wu, W. Wang, M. Su, and J. Gao, "A modified coupled-line Schiffman phase shifter with short reference line," Progress In Electromagnetics Research C, Vol. 54, 17-27, 2014.
17. Wu, Y., L. Yao, W. Wang, and Y. Liu, "A wide-band 180-degree phase shifter using a pair of coupled-line stubs," IEEE International Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meeting, 240-241, July 2015.
18. Bai, Y.-F., X.-H. Wang, C.-J. Gao, Q.-L. Huang, and X.-W. Shi, "Design of compact quad-frequency impedance transformer using two-section coupled line," IEEE Transactions on Microwave Theory and Techniques, Vol. 60, No. 8, 2417-2423, August 2012.