###### Abstract  
With the increase in applications of the millimeter wave spectrum for phased array radar systems, mobile 7-13 communication systems, and satellite systems, the demand for a wideband, high-efficiency, high-power monolithic microwave integrated circuit (MMIC) power amplifier (PA) is increasing. In this paper, a 7-13 GHz 10 W high-efficiency MMIC PA is designed. This amplifier consists of a two-stage circuit structure with two high electron mobility transistor (HEMT) cells for the driver stage and four HEMT cells for the power stage. To ensure high efficiency and a certain output power (\(P_{out}\)), both the driver-stage and power-stage transistors use a deep Class-AB bias. At the same time, in order to further improve the efficiency, low-loss and second-harmonic tuning techniques are used in the output and inter-stage matching networks, respectively. Finally, the electromagnetic simulation results show that within a frequency of 7-13 GHz, the amplifier achieves an average saturated continuous wave (CW) \(P_{out}\) of 40 dBm, a small signal gain of 14.5-15.5 dB, a power-added efficiency (PAE) of 30-46%, and the input and output return loss are better than 5 dB and 8 dB, respectively.  
high efficiency; power amplifier; 7-13 GHz; monolithic microwave integrated circuit; two-stage +
Footnote †: journal: Applied Physics Letters  
_Applied Physics Letters_  
**Citation:** [PERSON]; [PERSON]; [PERSON]; [PERSON]; [PERSON] A.7-13 GHz 10 W High-Efficiency MMIC Power Amplifier in 0.25 mm GaN HEMT Process. _Appl. Sci._**2022**, 12, 10872. [[https://doi.org/10.3390/app122110872](https://doi.org/10.3390/app122110872)]([https://doi.org/10.3390/app122110872](https://doi.org/10.3390/app122110872))  
Academic Editor: [PERSON]  
Received: 20 September 2022  
Accepted: 25 October 2022  
Published: 26 October 2022  
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**Cognition:** 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license ([[https://creativecommons.org/licenses/by/](https://creativecommons.org/licenses/by/)]([https://creativecommons.org/licenses/by/](https://creativecommons.org/licenses/by/))).  
**Cognition:** 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.  
size. In [27], a high-power single-chip X-band Class-F power amplifier was reported.. The fabricated Class-F PA delivered a bandwidth of 1.6 GHz at the point of 50% PAE, and a high power density of 4.42 W/mm was demonstrated. In conclusion, almost all of these results were achieved in a narrow frequency band. Therefore, achieving a high PAE while maintaining relatively high power in a wide bandwidth remains a design challenge.  
In this paper, a design procedure for a 7-13 GHz GaN MMIC PA is presented in detail, and the MMIC PA is designed in 0.25 um gate length GaN high electron mobility transistor (HEMT) technology. The remaining part of this paper is organized as follows: Section 2 presents the utilized GaN HEMT process. Section 3 shows the detailed design procedures of the proposed PA, the design of the driver and power stages of the MMIC PA, and the design of the impedance matching networks. In Section 4, the experimental results are presented, and a conclusion is given in Section 5.