# Highly Efficient GaN Doherty Power Amplifier for N78 Sub-6 GHz Band 5G Applications
## 5 Conclusions  
In conclusion, this paper proposed a design for a high-efficiency GaN Doherty power amplifier for 5G applications within the band of 3.3 to 3.8 GHz and compared its results to those of the traditional DPA design. This paper implemented an unequal Wilkinson power divider, which significantly boosted PAE from 41.7% to 52.6% compared to the traditional DPA design. Additionally, we introduced a seventh-order post-harmonic suppression network at the amplifier's output, effectively attenuating second- to fourth-order harmonics to levels exceeding \(-50\) dB. This enhancement not only improved linearity but also contributed to an overall increase in PAE, reaching 70.6% compared to the traditional DPA design. Consequently, our DPA design, incorporating both the unequal power divider and the post-harmonic suppression circuit, comprehensively enhances power amplifier performance in terms of gain, output power, and efficiency. To verify the simulation results, both the power divider and the harmonic suppression network were fabricated and measured. The simulation and measurement results are compared and showed good agreement, with some discrepancies due to unexpected variations during fabrication and assembly. The proposed DPA design achieved a gain of 12 dB, an output power of 42 dBm, a drain efficiency of 80%, and a power-added efficiency of 75.2%. These results demonstrate the suitability of the proposed power amplifier design for 5G applications in the sub-6 GHz  
Figure 27: The gain, output power, DE, and PAE for the proposed DPA from 3.1 GHz to 4 GHz.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Ref.** & **Frequency (GHz)** & **Pout (dBm)** & **PAE (\%)** & **Gain (dB)** & **Transistor** \\ \hline
[6] & 2.8–3.3 & 43–44.2 & 62–76.5 (DE) & 8–13.5 & CGH40010F \\
[7] & 2.9-3.3 & 43–94.7 & 70.8–73.3 (DE) & 6–11 & CGH40010F \\
[33] & 4.5–5.3 & 39.5 & 44–54 & 11 & H�WAREFR 0.25 \(\upmu\) GaN \\
[34] & 1.7–2.2 & 42.5 & 58–72 & 8.2–10.2 & 10 W Cree GaN HEMT \\
[35] & 1.2–1.6 & 33 & 60 & 19 & GaAs pHEMT \\
[36] & 1.4–2.1 & 34 & 35.7 & 12.7 & CGH40010F \\
[37] & 3.4–3.8 & 43 & 70 & 8 & CGZH40010F \\
[38] & 3.5–4 & 41.7 & 49.6 & 11.1 & CGH40006S \\
[39] & 4.1–5.6 & 38.4-39.5 & 41.2–49 & 8.3–11.2 & GaN MMIC \\
[40] & 3–3.6 & 43–44 & 55–66 (DE) & 12 & CGH40010F \\ This Work & 3.3-3.8 & 42 & 75.2 & 12.2 & CGZH40010F \\ \hline \hline \end{tabular}
\end{table}
Table 3: Performance comparison of this work with similar works based on simulation.  
N78 band, which is the most widely used band in active 5G NR networks. Additionally, this research represents a noteworthy contribution to the field of RF power amplifiers for 5G applications and offers potential avenues for further studies in this domain.  
Conceptualization, M.A.E.E. and T.G.A.; Methodology, M.A.E.E., T.G.A. and H.A.I.; Software, M.A.E.E. and T.G.A.; Validation, T.G.A. and H.A.I.; Formal analysis, T.G.A., E.K.I.H. and M.A.; Investigation, H.A.I.; Data curation, A.J.A.A.-G. and M.A.; Writing--original draft, M.A.E.E. and T.G.A.; Writing--review & editing, M.A.E.E., E.K.I.H., A.J.A.-G., T.A.H.A. and M.A.; Visualization, T.A.H.A. and M.A.; Supervision, T.G.A., H.A.I., E.K.I.H. and M.A.; Project administration, A.J.A.-G. and M.A. All authors have read and agreed to the published version of the manuscript.  
This research is supported by the Researchers Supporting Project (RSPD2023R868), King Saud University, Riyadh, Saudi Arabia.  
The data presented in this study are available on request from the corresponding authors.  
The authors would like to acknowledge the support provided by the Researchers Supporting Project, King Saud University, Riyadh, Saudi Arabia. Furthermore, the authors would like to extend their appreciation to Universiti Teknikal Malaysia Melaka (UTeM) and the Ministry of Higher Education of Malaysia (MOHE).  
The authors declare no conflict of interest.