![]() The implemented design is targeted for application in the phased-array antenna structure for 5G base stations, which support the n257 (26.5–29.5 GHz) and n261 (27.5–28.35 GHz) bands of the 5G NR frequency range 2 (FR2). By adopting series inductors at the drains of the device, the reverse isolation and stability performance of the amplifier are eventually improved at the operating frequency with minimum impact on the overall MAG and noise figure (NF) performance. In this study, we demonstrate a 26–30 GHz GaN HEMT LNA monolithic microwave integrated circuit (MMIC) using a 0.15-μm GaN-on-silicon carbide (SiC) process. This eventually causes an extra design trade-off between stability and maximum available gain (MAG) performance. Specifically, in the mmWave frequency range, high frequency path losses and parasitic capacitance readily affect isolation characteristics. However, in the design of GaN HEMT-based amplifiers, stability performance is also a major concern, which is directly related to the reverse isolation characteristic ( S12) of the amplifier. Because of these benefits, various GaN HEMT-based LNAs have been reported in recent studies. Moreover, as the scaling of GaN technology shrinks and corresponding breakdown voltage increases, the noise characteristic of GaN devices becomes comparable to that of their GaAs and indium phosphide (InP) counterparts. Therefore, through the elimination of these extra protection circuits, reduced size and improved noise performance can be realized in the FEM design with the additional possibility of a low-cost single-chip solution by integrating the LNA, PA, and SPDT within a single die. On the other hand, a GaN HEMT-based LNA with a single-pole double-throw (SPDT) switch ( Figure 1b) no longer needs those protection circuits owing to their own inherent high-power endurance. However, as depicted in Figure 1a, the limited high-power robustness of GaAs devices necessitates additional protection circuits such as an isolator and/or a limiter at the input of the receiver front end, which substantially exacerbates the design complexity and noise performance of the FEM design. In fact, FEMs using gallium arsenide (GaAs) technology have been widely utilized in various wireless applications over the last decade because GaAs devices generally provide good electron mobility and noise characteristics. īased on the supremacy of GaN devices, the research and development of the GaN HEMT-based LNAs has also been intensified from the perspective of design simplicity, low cost, and enhanced noise performance. For this reason, GaN HEMT devices have been widely used in various PA implementations to endure modulated high-power RF signals. ![]() ![]() This is primarily attributed to the wide energy bandgap (3.4 eV), high saturation velocity (>2.5 × 10 5 m/s), and high breakdown voltage (>100 V) of GaN HEMT devices. In practice, the GaN HEMT device has its own distinct merit with regard to its high power handling capability. To satisfy these requirements, a gallium nitride (GaN) high electron mobility transistor (HEMT) has been considered as an attractive candidate for the FEM design of mmWave 5G NR base station applications. Therefore, small-size, low-cost, and high-linearity radio frequency (RF) front-end modules (FEMs) that integrate low-noise amplifiers (LNAs), high-power amplifiers (PAs), and transmitter/receiver switches are in high demand, specifically for base station applications. In reality, the envisioned mmWave 5G NRs adopt massive multiple-input multiple-output (MIMO) technology that utilizes a phased-array antenna configuration. Therefore, extensive research has been conducted to develop and secure high-performance, low-cost, and highly reliable solutions in preparation for full-scale deployment of 5G base stations. Recently, the commercialization of millimeter-wave (mmWave) fifth-generation (5G) new radio (NR) communication has been actively attempted in various countries to cope with the explosive increase in mobile data traffic.
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