IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES 1 A Power Ampliﬁer Using Hetero-Dielectric Matching Circuits Weiming Ma , Yang Gao , Member, IEEE, Menghan Sun , Di Lu , Member, IEEE, Pengcheng Jia, Student Member, IEEE, and Ming Yu , Fellow, IEEE Abstract—This article presents RF and microwave power ampliﬁers (PAs) that utilize hetero-dielectric (HD) lumped ele- ments in matching circuits. The proposed innovative model achieves a higher Q-factor due to its unique electromagnetic (EM) properties compared with conventional on-chip (OC) lumped elements and microstrip circuits. For the ﬁrst time, formulas for calculating the parameters of the equivalent lumped elements of the model are given. This HD lumped element with a high Q-factor reduces the matching circuit loss and further improves the performance of the PA. The design of the PA based on an HD model has been theoretically explored and experimentally validated using 0.25-μm GaN HEMTs microwave integrated circuits (MICs) at 2.8–3.6 GHz. The drain eﬃciency (DE) ranges from 53.6% to 63.2% at an output power of 33.5–35.3 dBm, and the adjacent channel leakage power ratios (ACLRs) are -38.1 dBc. High Q-factor passive elements based on this model are expected to play an important role in realizing OC low-insertion loss ﬁlters and high-eﬃciency PAs. Index Terms—Hetero-dielectric (HD), high Q-factor, lumped element, power ampliﬁer (PA). Received 24 June 2025; revised 24 August 2025 and 17 September 2025; accepted 18 September 2025. This work was supported in part by Guangdong Science and Technology Programme under Grant 2024B0101020003; in part by China Postdoctoral Science Foundation under Grant 2023M733202; in part by Guangdong Innovative and Entrepreneurial Research Team Program under Grant 2021ZT09X256; in part by the High Level of Special Funds under Grant G03034K004; and in part by Ming Yu’s Oﬃce, Fellow of the Canadian Academy of Engineering, founded with Starway Communication Company Ltd. (Corresponding authors: Yang Gao; Ming Yu.) Weiming Ma is with the National Key Laboratory of Radar Detection and Sensing and the School of Electronic Engineering, Xidian University, Xi’an 710071, China, and also with Shenzhen Key Laboratory of EM Information and the Department of Electronic and Electrical Engineering, Southern University of Science and Technology, Shenzhen 518055, China. Yang Gao is with Shenzhen Key Laboratory of EM Information and the Department of Electronic and Electrical Engineering, Southern Uni- versity of Science and Technology, Shenzhen 518055, China (e-mail: gaoyang678@outlook.com). Menghan Sun is with the Department of Electrical and Electronic Engi- neering, The University of Hong Kong, Hong Kong, SAR. Di Lu is with the State Key Laboratory of Radio Frequency Heterogeneous Integration, College of Electronics and Information Engineering, Shenzhen University, Shenzhen 518060, China. Pengcheng Jia is with Starway Communication Company Ltd., Guangzhou 510000, China. Ming Yu is with Shenzhen Key Laboratory of EM Information and the Department of Electronic and Electrical Engineering, Southern University of Science and Technology, Shenzhen 518055, China, and also with the National Center for Applied Mathematics Shenzhen (NCAMS), Shenzhen 518055, China (e-mail: ming.yu@ieee.org). Digital Object Identiﬁer 10.1109/TMTT.2025.3612917 I. I NTRODUCTION P OWER ampliﬁers (PAs) are commonly employed in the ﬁnal stages of radar systems and RF transmitters to enhance signal power levels [1], [2], [3]. Achieving higher eﬃciency has always been a central requirement for PAs, since it profoundly aﬀects the energy consumption, service life, product cost, and market competitiveness of equipment [4], [5], [6], [7], [8], [9], [10]. Several factors contribute to reduced PA eﬃciency, including output capacitance losses and soft-switching losses in ﬁeld-eﬀect transistors (FETs) [11], [12], [13], improper bias point selection [14], and impedance mismatch [15]. When these factors remain unchanged, losses from low-Q-factor circuit components become the primary issue aﬀecting PA eﬃciency [16], [17]. Substantial research has been conducted to improve PA eﬃciency, with notable progress achieved in reducing ohmic losses in low-Q-factor matched circuits. For instance, an on-chip (OC) 3-D inductor was fabricated in [18] using a plastic deformation mag- netic assembly to increase the Q-factor from below 10 to 20–25. Fully CMOS-compatible micro-electromechanical systems (MEMS) inductors with Q-factors reaching 70 at 6 GHz are reported in [19]. Utilizing high-aspect-ratio silver micromachining technology, inductors with Q-factors of 50–80 have been realized in the S band [20]. A concave-suspended solenoid inductor with a 2.96-nH inductance at 5.35 GHz and a peak Q-factor of ∼45 is reported in [21]. Fig. 1 quantitatively assesses the Q-factors of diﬀerent inductor types in the RF/microwave band. It is evident that CMOS, GaAs, and GaN substrates with OC inductors exhibit Q-factors below 40 [22], [23], [24], [25], [26], [27]. This limitation stems partly from excessive losses generated by inductor coils on semiconductor substrates at microwave fre- quencies and partly from self-resonance caused by parasitic capacitance between the inductor coil and substrate [28], [29]. To achieve higher Q-factors, engineers employ gold bonding- wire inductors and wire-wound inductors [30], [31], [32], [33], yielding values 2× to 3× greater than OC inductors. As shown in Table I, the reported hetero-dielectric (HD) inductors achieved a Q-factor 3×–4× higher than those of MEMS and 3-D inductor, with only a slight increase in footprint. Herein, we present a high-Q HD circuit for PA matching networks to improve PA eﬃciency. As Fig. 1 illustrates, this HD inductor achieves a Q-factor exceeding 200 in the S band, which is about 2×–3× higher than conventional elements, 0018-9480 © 2025 IEEE. All rights reserved, including rights for text and data mining, and training of artiﬁcial intelligence and similar technologies. 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