The cost will be reduced as market demand increases, and GaN is not far from the commercial market.

In recent years, due to its higher power output and smaller footprint at high frequencies, GaN has been widely adopted by the RF industry. The entire GaN RF market is expected to grow to $2 billion by 2024, driven by two major applications: telecommunications infrastructure and defense. A research report by industry research firm Yole Développement (Yole) pointed out that global telecommunications infrastructure investment has remained stable over the past decade. In this market, the trend towards higher frequencies provides an optimal driving force for the development of RF GaN in PAs with frequencies below 6 GHz in 5G networks.

Since the first commercial products appeared 20 years ago, GaN has become a serious competitor to LDMOS and GaAs in RF power applications, continuously improving performance and reliability at lower costs. The first GaN-on-SiC and GaN-on-Si components appeared almost simultaneously, but GaN-on-SiC has become more mature in technology. GaN-on-SiC currently dominates the GaN RF market, has penetrated the 4G LTE wireless infrastructure market, and is expected to be deployed in 5G sub-6GHz RRH architectures. However, in the meantime, significant progress has been made in cost-effective LDMOS technology, which may challenge GaN solutions in 5G sub-6Ghz active antennas and massive MIMO deployments.

The overall size of the GaN market was approximately US$645 million in 2018, with wireless communication applications accounting for approximately US$304 million, military applications accounting for approximately US$270 million, and aerospace applications accounting for US$37 million as the three major applications. In 2024, the overall market will grow to US$20.013 billion, with a CAGR of 21%. The scale of wireless communication applications will reach US$752 million, and that of military applications will be US$977 million. It is worth noting that RF Energy will grow from US$2 million to US$104 million.

Further reading: Why are so many people optimistic about gallium nitride?

GaN belongs to the third generation of semiconductor materials with high bandgap width . Compared with its predecessors such as the first generation Si and the second generation GaAs, it has outstanding advantages in characteristics. Due to its large bandgap width and high thermal conductivity, GaN devices can operate at high temperatures above 200°C, can carry higher energy density, and have higher reliability; the larger bandgap width and insulation breakdown electric field reduce the on-resistance of the device, which is beneficial to improving the overall energy efficiency of the device; the fast electron saturation velocity and high carrier mobility allow the device to operate at high speed.

Therefore, by using GaN, people can obtain semiconductor devices with wider bandwidth, higher amplifier gain, higher energy efficiency and smaller size, which is consistent with the consistent "tone" of the semiconductor industry.

Compared with GaN, the application research of SiC, which is also a third-generation semiconductor material, actually started earlier. There are two main reasons why GaN has become more eye-catching in recent years.

First, GaN has shown stronger potential in reducing costs. Currently, mainstream GaN technology manufacturers are developing GaN devices with Si as the substrate to replace the expensive SiC substrate. Some analysts predict that by 2019, the cost of GaN MOSFET will be comparable to that of traditional Si devices, and a market inflection point is likely to appear at that time. And this technology is an attractive market opportunity for suppliers, as it can provide their customers with performance that may not be achieved by current semiconductor process materials.

Secondly, since GaN devices are planar devices, they are highly compatible with existing Si semiconductor processes, making them easier to integrate with other semiconductor devices. For example, some manufacturers have already achieved the integration of driver ICs and GaN switch tubes, further lowering the user's usage threshold.

Based on the above characteristics of GaN, more and more people are optimistic about its future development. In particular, GaN has shown considerable penetration in several key markets.

1. Application of GaN in 5G

RF GaN technology is a perfect match for 5G, and base station amplifiers use GaN. Gallium nitride (GaN), gallium arsenide (GaAs) and indium phosphide (InP) are commonly used semiconductor materials in RF applications.

Compared with high-frequency processes such as gallium arsenide and indium phosphide, gallium nitride devices have higher output power; compared with power processes such as LDCMOS and silicon carbide (SiC), gallium nitride has better frequency characteristics. Gallium nitride devices have higher instantaneous bandwidth, which is very important. The use of carrier aggregation technology and the preparation of using higher frequency carriers are all aimed at obtaining larger bandwidth.

Gallium nitride is faster than silicon or other devices. GaN can achieve higher power density. For a given power level, GaN has the advantage of being small. With smaller devices, device capacitance can be reduced, making the design of higher bandwidth systems easier. A key component in RF circuits is the PA (Power Amplifier).

From the current application perspective, power amplifiers are mainly composed of gallium arsenide power amplifiers and complementary metal oxide semiconductor power amplifiers (CMOS PA), among which GaAs PA is the mainstream. However, with the advent of 5G, gallium arsenide devices will not be able to maintain high integration at such high frequencies.

Therefore, GaN has become the next hot spot. As a wide bandgap semiconductor, GaN can withstand higher operating voltages, which means that its power density and operating temperature are higher. Therefore, it has the characteristics of high power density, low energy consumption, suitable for high frequencies, and supports wide bandwidth.

Cristiano Amon, president of Qualcomm, said at the 2018 Qualcomm 4G/5G Summit: It is expected that there will be two waves of 5G mobile phones on the market in the first half of next year and the Christmas and New Year period at the end of the year, and the first batch of commercial 5G mobile phones will be launched soon. According to reports, 5G technology is expected to provide speeds 10 to 100 times faster than the current 4G network, reaching the level of gigabits per second, and can more effectively reduce latency.

In the application of Massive MIMO, a key technology of 5G, a large number (such as 32/64) of array antennas are used on the base station transceiver to achieve greater wireless data traffic and connection reliability. This architecture requires a corresponding RF transceiver unit array, so the number of RF devices will increase greatly. The size of the device is critical. The small size, high efficiency and high power density of GaN can be used to achieve highly integrated solutions, such as modular RF front-end devices.

At the same time, in 5G millimeter wave applications, GaN's high power density characteristics can effectively reduce the number of transceiver channels and the size of the overall solution while achieving the same coverage conditions and user tracking functions, achieving the optimal combination of performance and cost.

In addition to the greatly increased number of RF devices required in the display of the base station RF transceiver unit, the base station density and the number of base stations will also increase greatly. Therefore, compared with the 3G and 4G eras, the number of RF devices in the 5G era will increase by dozens or even hundreds of times. Therefore, cost control is very critical, and silicon-based gallium nitride has huge advantages in cost. With the maturity of silicon-based gallium nitride technology, it can achieve a breakthrough in the market with the greatest cost-effectiveness advantage.

2. Application of GaN in the fast charging market

As the screens of electronic products become larger and larger, the power of chargers also increases, especially for high-power fast-charging chargers. The use of traditional power switches cannot change the current status of chargers.

GaN technology can do this because it is currently the world's fastest power switching device and can maintain high efficiency levels under high-speed switching conditions. It can be applied to smaller components and can effectively reduce the size of the product when used in chargers. For example, the current typical 45W adapter design can adopt a 25W or smaller form factor design.

Gallium nitride chargers have attracted global attention. Their high speed, high frequency and high efficiency make high-power USB PD chargers no longer bulky bricks. They can achieve high-power output in a small size and are smaller and lighter than APPLE's original 30W charger.

Put the built-in gallium nitride charger and the traditional charger side by side. The output power of the built-in gallium nitride charger reaches 27W, and the output power of the APPLE USB-C charger is 30W. The power difference between the two is not much, but the size is completely different. The built-in gallium nitride charger is 40% smaller than the Apple charger.

According to incomplete statistics, as of October 23, 2018, there are 52 mobile phones on the market that support USB PD fast charging. Almost all mainstream mobile phone manufacturers have incorporated the USB PD fast charging protocol into the charging configuration of their mobile phones, including first-tier brands such as Apple, Huawei, Xiaomi, and Samsung.

Judging from the layout of major mobile phone manufacturers and chip manufacturers, USB PD fast charging will become the preferred charging solution for electronic devices such as mobile phones, game consoles, and laptops, and USB Type-C will also become the only interface for power and data transmission between electronic devices in the next decade. The unified situation of USB PD fast charging protocol is about to come.