Why is the GaN device [G-level is negative voltage powered]

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Why is the GaN device [G-level is negative voltage powered] [Copy link]

We all know that before GaN, we rarely used negative voltage in RF amplification or [base station amplification], but after GaN came, everything changed.

The following is an interpretation of the three materials and the development trends of domestic and foreign manufacturers.

GaN will have obvious advantages in the high-power and high-frequency RF markets

GaN high electron mobility transistors (HEMTs) have become the mainstream candidate technology for 5G macro base station power amplifiers. With their inherent high breakdown voltage, high power density, large bandwidth and high efficiency, GaN HEMTs have become a strong candidate technology for base station PAs.

GaN is an extremely stable compound with strong atomic bonds, high thermal conductivity, the highest degree of ionization among III-V compounds, and good chemical stability, making GaN devices more resistant to radiation than Si and GaAs. At the same time, GaN is a high melting point material with high thermal conductivity. GaN power devices usually use SiC with better thermal conductivity as the substrate. Therefore, GaN power devices have a higher junction temperature and can operate in high temperature environments.

Power-frequency operating range of RF devices with different material systems

GaN will have obvious advantages in high-power and high-frequency RF markets

Compared with 4G, the communication frequency band of 5G has migrated to the high-frequency band. At present, the communication frequency band of 4G network in my country is mainly 2.6GHz. In 2017, the Ministry of Industry and Information Technology released the frequency use plan of 5G system in the 3-5GHz frequency band (mid-frequency band), and will gradually add high-frequency bands above 6GHz as capacity coverage in the future. Compared with Si-based lateral diffused metal oxide semiconductor (Si LDMOS, Lateral Double-diffused Metal-oxide Semiconductor) and GaAs, GaN RF devices at the base station end can more effectively meet the high power, high communication frequency band and high efficiency requirements of 5G.

Currently, there are two main types of power amplifiers for the 3G and LTE base station markets: Si LDMOS and GaAs. However, the bandwidth of LDMOS power amplifiers will decrease significantly as the frequency increases, and is only effective within a frequency range of approximately 3.5 GHz. Although GaAs power amplifiers can meet the needs of high-frequency communications, their output power is much inferior to that of GaN devices. However, GaN RF devices have not yet begun to be used on a large scale in the mobile terminal field due to their high production costs and supply voltage. GaN will play an important role in the high-power, high-frequency RF market.

The figure below shows the millimeter-wave 5G base station MIMO antenna solutions of silicon germanium and gallium nitride. The one on the left is a silicon germanium-based MIMO antenna, which has 1024 elements, a die area of 4096 square millimeters, and a radiation power of 65dbm. In sharp contrast, the gallium nitride-based MIMO antenna on the right, although more expensive, has a 40% reduction in power consumption and a 94% reduction in die area.

Source: Guojin Securities

According to Yole's forecast, the market size of GaN RF devices reached US$457 million in 2018, with a compound growth rate of more than 23% in the next five years. In the entire RF application market, the market share of GaN devices will gradually increase. In the long run, in the field of macro base stations and backhaul, GaN will gradually replace LDMOS and GaAs to occupy a dominant position with its high-frequency and high-power performance advantages; in the field of RF energy, LDMOS is expected to occupy a major market share with its high-power and low-cost advantages; in other fields with relatively low output power requirements, GaAs and GaN will form a pattern of co-dominance.

At present, LDMOS, GaAs and GaN almost divide the entire RF market into three parts, but the market share of LDMOS will gradually shrink in the future, and part of the market will be replaced by GaN. GaAs relies on the demand brought by the growing small base stations and the higher defense market. Before 2025, its market share will be relatively stable overall.

In the next 5 to 10 years, GaN will gradually replace LDMOS and gradually become the mainstream technology for RF power applications of 3W and above. GaAs will ensure its stable market share with its market-proven reliability and cost-effectiveness. The market share of LDMOS will gradually decline and will drop to about 15% of the overall market size during the forecast period. It is predicted that by 2023, the market revenue of GaNRF devices is expected to reach US$1.3 billion, accounting for about 45% of the RF power market above 3W.

Key companies and product progress in the overseas GaN RF device industry chain:

Although the microwave radio frequency field has attracted much attention at present, due to the high technical level and large patent barriers, there are not many companies in this field compared with the power electronics and optoelectronics fields, but most of them have strong scientific research strength and market operation capabilities.

73% of Qorvo, CREE, and MACOM's product output power is concentrated between 10W and 100W, and the maximum power reaches 1500W (operating frequency is 1.0-1.1GHz, produced by Qorvo). The technology used is mainly GaN/SiC GaN route. In addition, some companies provide GaN RF module products. Currently, there are 4 companies that provide sales of GaN RF amplifiers. Among them, Qorvo products have the largest operating frequency range, and the maximum operating frequency can reach 31GHz. Skyworks products have a relatively small operating frequency, mainly concentrated between 0.05-1.218GHz.

Key companies and product developments in the GaN RF device industry chain in mainland China:

Due to concerns about the speed of my country's technological development and the idea of curbing the development of my country's new material technology, European and American countries have almost completely blocked my country's technology and materials in the third-generation semiconductor materials. Under this circumstance, my country's scientific research institutions and enterprises have relied on independent innovation and have achieved remarkable results in the field of GaN microwave radio frequency, and have made breakthroughs in the military and defense fields and the civil communications fields, creating key enterprises such as China Electronics Technology Group Corporation 13th Institute, China Electronics Technology Group Corporation 55th Institute, ZTE Communications, Datang Mobile, and major customers such as China Mobile and China Unicom.

Suzhou Enerxun has launched RF power transistors with a frequency of up to 6GHz, an operating voltage of 48V, and a design power range of 10W-320W. In terms of mobile communications, Suzhou Enerxun can already provide high-efficiency and high-gain RF power amplifiers suitable for mobile communication applications such as LTE, 4G, and 5G, with an operating frequency of 1.8-3.8GHz, an operating voltage of 48V, a design power range of 130W-390W, and an average power of 16W-55W.