volume | PIER Journals

Abstract

Achieving simultaneous wideband operation and high output power efficiency remains a major challenge in modern GaN HEMT power amplifier (PA) design, particularly for broadband communications and radar systems. This paper presents a systematic design methodology for a broadband PA that integrates radial-stub (RS)-based bias/matching networks with an algorithmic gate-bias (V_GS) optimization, alongside load-pull-derived device termination and compact layout. Starting with theWolfspeed CMPA0530002S GaN HEMT, which features intrinsic broadband stability and an integrated input match, we replace conventional narrowband bias lines with a radial-stub network that ensures broadband bias isolation and low-loss matching. A thorough load-pull study identifies the optimum load impedance for concurrent maximization of power-added efficiency (PAE), gain, and output power. Subsequently, an automated V_GS sweep across the full 1.16-1.6 GHz band determines the optimal bias point for broadband and efficiency trade-off. The PA achieves a simulated result of output power of 34.28 dBm , flat gain of approximately 13.28 dB, and a peak PAE of 58.69% in a fractional bandwidth of 37% (1.16-1.6 GHz). A key novelty of this work lies in the proposed algorithmic V_GS sweep technique, which enables optimization of broadband efficiency throughout the entire 1.16-1.6 GHz operating band and can be easily extended to other frequency ranges. Unlike conventional bias optimization methods that are limited to a single frequency, the proposed algorithm systematically identifies the optimal gate bias across multiple frequencies to maintain high efficiency and consistent output power over a wide bandwidth. The simulated results confirm that this algorithmic bias optimization approach achieves superior broadband efficiency and stable output performance, providing a scalable and adaptable design methodology for next-generation wireless communication and electronic warfare systems.

1. Naik, Gaurang, Jung-Min Park, Jonathan Ashdown, and William Lehr, "Next generation Wi-Fi and 5G NR-U in the 6 GHz bands: Opportunities and challenges," IEEE Access, Vol. 8, 153027-153056, 2020.
doi:10.1109/access.2020.3016036 Google Scholar

2. Mabrok, Mussa, Zahriladha Zakaria, and Nasrullah Saifullah, "Design of wide-band power amplifier based on power combiner technique with low intermodulation distortion," International Journal of Electrical and Computer Engineering (IJECE), Vol. 8, No. 5, 3504-3511, Oct. 2018.
doi:10.11591/ijece.v8i5.pp3504-3511 Google Scholar

3. Erunkulu, Olaonipekun Oluwafemi, Adamu Murtala Zungeru, Caspar K. Lebekwe, Modisa Mosalaosi, and Joseph M. Chuma, "5G mobile communication applications: A survey and comparison of use cases," IEEE Access, Vol. 9, 97251-97295, 2021.
doi:10.1109/access.2021.3093213 Google Scholar

4. Cripps, Steve C., RF Power Amplifiers for Wireless Communications, 2nd Ed., Artech House, Norwood, MA, 2006.

5. Amar, Ahmed S. I., Manish Mamidanna, Mohammad Darwish, and Hadia El-Hennawy, "High gain broadband power amplifier design based on integrated diplexing networks," IEEE Microwave and Wireless Components Letters, Vol. 32, No. 2, 133-136, Feb. 2022.
doi:10.1109/lmwc.2021.3122075 Google Scholar

6. Cai, Qi, Wenquan Che, and Quan Xue, "High-efficiency power amplifier with a multiharmonic tuning network," IEEE Microwave and Wireless Components Letters, Vol. 31, No. 4, 389-392, Apr. 2021.
doi:10.1109/lmwc.2021.3055235 Google Scholar

7. Feng, Wenjie, Wenbin Wu, Xin Yu Zhou, Wenquan Che, and Yongrong Shi, "Broadband high-efficiency quasi-Class-J power amplifier based on nonlinear output capacitance effect," IEEE Transactions on Circuits and Systems II: Express Briefs, Vol. 69, No. 4, 2091-2095, 2022.
doi:10.1109/tcsii.2022.3141423 Google Scholar

8. Sun, Jia Xing, Feng Lin, Bo Li, Houjun Sun, and Wenhua Chen, "Continuous Class-J/F-1 mode asymmetrical Doherty power amplifier with extended bandwidth and enhanced efficiency," IEEE Transactions on Microwave Theory and Techniques, Vol. 71, No. 11, 4814-4825, Nov. 2023.
doi:10.1109/tmtt.2023.3275177 Google Scholar

9. Sheikhi, Akram, "Historical aspect of load-modulated balanced amplifiers," IEEE Access, Vol. 12, 7974-7986, 2024.
doi:10.1109/access.2024.3351835 Google Scholar

10. Nikandish, Gholamreza, Robert Bogdan Staszewski, and Anding Zhu, "Breaking the bandwidth limit: A review of broadband Doherty power amplifier design for 5G," IEEE Microwave Magazine, Vol. 21, No. 4, 57-75, 2020.
doi:10.1109/mmm.2019.2963607 Google Scholar

11. Mabrok, Mussa, Zahriladha Zakaria, Tole Sutikno, and Ammar Alhegazi, "Wideband power amplifier based on Wilkinson power divider for S-band satellite communications," Bulletin of Electrical Engineering and Informatics, Vol. 8, No. 4, 1531-1536, 2019.
doi:10.11591/eei.v8i4.1552 Google Scholar

12. Boumalkha, Mohamed, Ahmed Gamal Abdellatif, Ahmed S. I. Amar, Mohammed Lahsaini, Amir Almslmany, Shuja Ansari, Mohammed Alammar, and Mahmoud A. Shawky, "Investigating broadband filtering power amplifier using multi-mode resonator-based bandpass filter," Results in Engineering, Vol. 26, 105035, 2025.
doi:10.1016/j.rineng.2025.105035 Google Scholar

13. Sayed, Ahmed, Sebastian Preis, and Georg Boeck, "Efficient technique for ultra broadband, linear power amplifier design," International Journal of Microwave and Wireless Technologies, Vol. 4, No. 6, 559-567, 2012.
doi:10.1017/s1759078712000578 Google Scholar

14. Ćwikliński, Maciej, Christian Friesicke, Peter Brückner, Dirk Schwantuschke, Sandrine Wagner, Roger Lozar, Hermann Maßler, Rüdiger Quay, and Oliver Ambacher, "Full W-band GaN power amplifier MMICs using a novel type of broadband radial stub," IEEE Transactions on Microwave Theory and Techniques, Vol. 66, No. 12, 5664-5675, 2018.
doi:10.1109/tmtt.2018.2878725 Google Scholar

15. Wang, Zhebin and Chan-Wang Park, "Novel wideband GaN HEMT power amplifier using microstrip radial stub to suppress harmonics," 2012 IEEE/MTT-S International Microwave Symposium Digest, 1-3, Montreal, QC, Canada, Jun. 2012.
doi:10.1109/MWSYM.2012.6259464

16. Mustafa, Sajjad Mohanad, Mohsen Hayati, Mehrnaz Khodadoost, Salma Ali Sadeq, Farzin Shama, and Pouya Karami, "Compact microstrip lowpass filter with wide stopband and sharp transition band using radial stub resonator," AEU --- International Journal of Electronics and Communications, Vol. 186, 155468, 2024.
doi:10.1016/j.aeue.2024.155468 Google Scholar

17. Wan, Fayu, Yexiang Xu, and Blaise Ravelo, "Radial stub based negative group delay circuit theory," IET Microwaves, Antennas & Propagation, Vol. 14, No. 6, 515-521, 2020.
doi:10.1049/iet-map.2019.0642 Google Scholar

18. Zhao, Junding, Shuai Wang, Xiaoqing Chen, Wei Lv, Zhe Li, and Hao Jiang, "Miniaturized microstrip branch-line coupler with wideband harmonic suppression using modified radial stub loaded resonators," 2023 15th International Conference on Communication Software and Networks (ICCSN), 358-360, Shenyang, China, Jul. 2023.
doi:10.1109/ICCSN57992.2023.10297401

19. Wang, Zhebin and Chan-Wang Park, "Novel wideband high-efficiency high-power amplifier using microstrip radial stub for 4G communication systems," Microwave and Optical Technology Letters, Vol. 56, No. 6, 1412-1418, Jun. 2014.
doi:10.1002/mop.28369 Google Scholar

20. Vardhan, Sri Harsha, Deepali Pathak, Raja Ramalingam, Manish Mehnde, and Ashudeb Dutta, "Microstrip radial stub based 4W GaN MMIC power amplifier for X-band radar applications," 2021 International Conference on Advances in Electrical, Computing, Communication and Sustainable Technologies (ICAECT), 1-4, Bhilai, India, Feb. 2021.
doi:10.1109/ICAECT49130.2021.9392405

21. Mohammadi, B., J. Nourinia, Ch. Ghobadi, and A. Valizade, "Design and analysis of the stub and radial-stub loaded resonator band-pass filter with cross-shaped coupled feed-lines for UWB applications," Applied Computational Electromagnetics Society Journal (ACES), Vol. 28, No. 9, 851-857, 2021. Google Scholar

22. Sharifi, Mohammad and Valiollah Mashayekhi, "Design of a modified Hairpin bandpass filter using embedded radial stubs featuring ultrawide stopband," AEU --- International Journal of Electronics and Communications, Vol. 164, 154624, 2023.
doi:10.1016/j.aeue.2023.154624 Google Scholar

23. Kwon, Hyukjin, Hongwook Lim, and Bongkoo Kang, "Design of 6-18 GHz wideband phase shifters using radial stubs," IEEE Microwave and Wireless Components Letters, Vol. 17, No. 3, 205-207, Mar. 2007.
doi:10.1109/lmwc.2006.890481 Google Scholar

24. Singh, Prashant Kumar, Anjini Kumar Tiwary, and Nisha Gupta, "Design of radial microstrip band pass filter with wide stop-band characteristics for GPS application," Progress In Electromagnetics Research C, Vol. 59, 127-134, 2015.
doi:10.2528/pierc15092001 Google Scholar

25. Nguyen, Duy P., Xuan-Tu Tran, Nguyen L. K. Nguyen, Phat T. Nguyen, and Anh-Vu Pham, "A wideband high efficiency Ka-band MMIC power amplifier for 5G wireless communications," 2019 IEEE International Symposium on Circuits and Systems (ISCAS), 1-5, Sapporo, Japan, May 2019.
doi:10.1109/ISCAS.2019.8702092

26. Mohamed, Eslam N., Ahmed M. Elelimy Abounemra, Mohammad Darwish, and Ayman M. El-Tager, "A generic multidimensional design methodology for highly efficient RF power amplifier with improved linearity," IEEE Transactions on Microwave Theory and Techniques, Vol. 72, No. 11, 6401-6413, 2024.
doi:10.1109/tmtt.2024.3396380 Google Scholar

27. Tan, J., K. S. Yuk, and G. R. Branner, "Design of a high power, wideband power amplifier using AlGaN/GaN HEMT," 2017 IEEE 18th Wireless and Microwave Technology Conference (WAMICON), 1-4, Cocoa Beach, FL, USA, Apr. 2017.
doi:10.1109/WAMICON.2017.7930252

28. Smorynski, Craig, MVT: A Most Valuable Theorem, Springer, 2017.
doi:10.1007/978-3-319-52956-1

29. Kim, Jihoon, "A review of Ku-band GaN HEMT power amplifiers development," Micromachines, Vol. 15, No. 11, 1381, 2024.
doi:10.3390/mi15111381 Google Scholar

30. Pozar, David M., Microwave Engineering, 4th Ed., John Wiley & Sons, Hoboken, NJ, 2012.

31. Boshnakov, Ivan, "Designing power amplifiers using maximum-efficiency lines and constant power contours," High Frequency Electronics, Vol. 18, No. 6, 28-34, Jun. 2019. Google Scholar

32. Bahl, Inder, Fundamentals of RF and Microwave Transistor Amplifiers, 1st Ed., John Wiley & Sons, Hoboken, NJ, 2009.
doi:10.1002/9780470462348

33. Gonzalez, G., Microwave Transistor Amplifiers: Analysis and Design, 2nd Ed., Prentice Hall, Upper Saddle River, NJ, 1996.

34. Merza, Marwah Ezzulddin and Khalid Khalil Mohamed, "Design and optimization of the GaN HEMT Class-J power amplifier for 2.4 GHz applications," 2024 21st International Multi-Conference on Systems, Signals & Devices (SSD), 509-518, Erbil, Iraq, 2024.
doi:10.1109/SSD61670.2024.10548613

35. Hietakangas, S., J. Typpo, and T. Rahkonen, "Integrated 1.6 GHz, 2W tuned RF power amplifier," 2008 NORCHIP, 176-179, Tallinn, Estonia, 2008.
doi:10.1109/NORCHP.2008.4738306

36. Kim, Woonyun, Ki Seok Yang, Jeonghu Han, Jae Joon Chang, and Chang Ho Lee, "An EDGE/GSM quad-band CMOS power amplifier," IEEE Journal of Solid-State Circuits, Vol. 49, No. 10, 2141-2149, Oct. 2014.
doi:10.1109/jssc.2014.2338873 Google Scholar

37. Refai, Wael Y. and William A. Davis, "A highly efficient linear multimode multiband Class-J power amplifier utilizing GaAs HBT for handset modules," IEEE Transactions on Microwave Theory and Techniques, Vol. 68, No. 8, 3519-3531, 2020.
doi:10.1109/tmtt.2020.3002161 Google Scholar

38. Alizadeh, Amirreza, Saleh Hassanzadehyamchi, Ali Medi, and Sayfe Kiaei, "An X-band Class-J power amplifier with active load modulation to boost drain efficiency," IEEE Transactions on Circuits and Systems I: Regular Papers, Vol. 67, No. 10, 3364-3377, Oct. 2020.
doi:10.1109/tcsi.2020.2991184 Google Scholar

39. Tang, W., L. Peng, S. Lin, G. Zhang, and Z. Zhang, "A broadband high efficiency Class-J power amplifier for C-band," Microwave Journal, May 2023. Google Scholar

40. Byeon, Chul-Woo and Joon-Hyung Kim, "2W HBT power amplifier module with dual second harmonic suppression technique," Sensors, Vol. 25, No. 4, 1231, Feb. 2025.
doi:10.3390/s25041231 Google Scholar

Dr. Ahmed Elrefaey

Dr. Fathi A. Faragb

Dr. Azhar A. Hamdi

Dr. Amir Almslmany