## 1 Introduction  
The fifth generation (5G) of mobile network technology offers high-speed data transmission, low latency, and a high data rate. It facilitates various applications, including multimedia services like high-definition video streaming as well as Internet of Things (IoT) applications, thus enabling the development of smart homes, smart cities, and autonomous driving. The expansion of 5G networks has led to a surge in demand for microcells in indoor settings such as homes, offices, factories, and warehouses. These microcells require radio frequency (RF) power in the range of 1-10 W to provide coverage over distances of 30-1000 m [1; 2]. Because microcells are typically powered by fixed cables, the supply voltage (which is typically around 4.2 volts) will not be limited by lithium-ion batteries. Utilizing higher supply voltages from the fixed power source enables the use of power amplifiers (PAs) that require higher voltages for efficient and high-power operation. While complementary metal oxide semiconductor PAs are cost-effective and commonly used in consumer products, they lack the linearity, efficiency, and output power needed for higher-power applications. Gallium arsenide (GaAs) heterojunction bipolar transistors and pseudo-morphic high-electron-mobility transistors (HEMT) offer higher power density and gain. GaAs technology is traditionally used in RF PAs [3; 4]. However,for sub-6 GHz microcell applications that require high output power, gallium nitride (GaN), HEMT technology offers clear advantages. GaN HEMT technology's wide bandgap, high electron saturation velocity, and high breakdown voltage enable higher RF output power due to higher DC voltage and power density compared to GaAs HEMT technology. GaN HEMT has seen a significant rise in its utilization across various applications [5; 6]. The use of discrete GaN HEMT components can achieve high performance and cost effectiveness [7; 8; 9]. However, for size-sensitive microcells, monolithic microwave integrated circuits (MMICs) and quasi-MMIC PAs are preferred. Despite the advantages of MMIC design in achieving a compact size, the cost of a fully integrated solution is relatively high. This cost consideration could pose challenges in meeting the demands of large-scale installations required by infrastructure providers. As a result, quasi-MMIC PAs with GaAs integrated passive device (IPD) technology are preferred for size-sensitive and price-sensitive microcells. They offer a balance between performance and cost effectiveness compared to MMIC designs with expensive GaN/SiC wafers. These quasi-MMIC PAs provide excellent performance while meeting size constraints and remaining cost-effective, making them an attractive choice for microcell applications [10; 11; 12; 13; 14; 15]. The [PERSON] power amplifier design is known for maintaining high efficiency at large output power back-offs. However, it faces challenges in achieving wide bandwidth due to the use of a load modulation network, which limits its frequency coverage [16]. Harmonic tuning can improve the efficiency of PAs, but it is limited by bulky quarter-wave transmission lines and LC resonators, affecting the operating bandwidth and chip area [17]. To achieve wide bandwidth without such limitations, continuous mode designs have been employed [18; 19; 20]. These continuous mode designs utilize simple matching networks, allowing for a broader frequency range and more efficient power amplification over a wider bandwidth. In this paper, two high-power high-efficiency broadband GaN quasi-MMIC PAs are introduced. The proposed PAs were fabricated in WIN(tm) Semiconductors' 0.25 \(\upmu\)m GaN/SiC HEMT technology and GaAs IPD technology. A continuous Class-J mode output matching network was designed to achieve excellent output performance. The chip-on-board (CoB) wire-bond assembly method was employed to ensure stability and efficient heat dissipation. The split design PA achieved a peak power of 40.3 dBm, while the stack design PA reached a peak power of 40 dBm.