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5G POWER ELECTRONICS The impact of 5G on power electronics

From Nigel Charig

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The 5G standard now being rolled out promises truly revolutionary advances in connectivity and communications. Equally, though, it is making significantly increased demands on the power electronics hardware that drives it. This article looks at why this is so, and how power electronics products are evolving to meet the challenge.

While being more powerful and functional than earlier standards, 5G also demands more power and better performance from its power electronics hardware.
While being more powerful and functional than earlier standards, 5G also demands more power and better performance from its power electronics hardware.
(Source: (C) Andrey Popov - AdobeStock)

5G is the new generation of wireless technology. It is so much more powerful than 4G and earlier generations that it does not just improve performance for existing device types; it is also opening up possibilities for entirely new services. As well as being fast, 5G supports greater data capacity, more connected devices, and instant responses with no latency.
One example of its capabilities would be a large, crowded sports stadium where everyone could use their mobile phones simultaneously without loss of performance. Another would be remote surgery, where the surgical instruments respond to operator commands without discernible delay.
While being more powerful and functional than earlier standards, 5G also demands more power and better performance from its power electronics hardware. As shown below, this applies to both the new infrastructures and the smartphone handsets being introduced to comply with the 5G standard.

5G base station architecture and power requirements

5G achieves its capabilities in part through using higher frequencies than previous cellular networks. However, higher-frequency radio waves have a shorter useful physical range, requiring smaller geographic cells. So, to maximize service, 5G networks operate on up to three frequency bands – low, medium, and high. These each provide different trade-offs between download speeds and service area or distance. 5G cell phones and wireless devices connect to the network through the highest speed antenna within range at their location.

Low-band 5G uses a similar frequency range to 4G cell phones, 600–850 MHz, giving download speeds a little higher than 4G: 30–250 megabits per second (Mbit/s). Low-band cell towers have a range and coverage area similar to 4G towers.
Mid-band 5G uses microwaves of 2.5–3.7 GHz, allowing speeds of 100–900 Mbit/s, with each cell tower providing service up to several kilometers in radius. This level of service is the most widely deployed, and should be available in most metropolitan areas. Some regions are not implementing low-band, making this the minimum service level.
High-band 5G uses frequencies of 25–39 GHz, near the bottom of the millimeter wave band. Its performance is comparable to that of cable internet, however, due to its limited range and high cost, planned deployments are limited to dense urban environments and areas like convention centers, or sports stadiums where crowds of people congregate.

As 5G deployment increases, improved power density will be required as more base stations are installed. The new frequencies can also create power efficiency problems. This is driving market demand, and creating a need for new solutions that reduce power consumption and form factor dimensions while providing higher performance. Market demand for RF power semiconductors is being stimulated in particular by mid-band products, due to their high deployment levels. Spending on devices rated below 4GHz and above 3W power grew in 2019 to nearly USD2 billion according to an ABI Research market data report.

As this market is growing, an increasing share is being taken by Gallium Nitride (GaN) devices, due to their improved performance. This is a development of a trend where RF power amplifiers based on gallium arsenide (GaAs), GaN, and silicon carbide (SiC) technologies started to gain traction during the advent of 4G. In addition, SiC devices offer lower costs and better performance than silicon (Si), and GaN-on-SiC can provide the best overall value. In particular, GaN-on-SiC offers three times the thermal conductivity of GaN-on-Si.

Meanwhile, GaN and GaAs power semiconductors have more advantages over traditional Si-based semiconductors, such as higher switching speed, lower electrical current loss, and higher power density. Material suppliers are implementing new manufacturing solutions to offer lower costs and easier adoption. In particular, further progress is expected in the manufacturing process of GaN and GaAs compound semiconductors.

Laterally-diffused MOS (LDMOS) plays an important role in power semiconductors, but GaN continues its race to gain market share, solving the many technical challenges as the market requires by bridging the gap with other much older, Si-based technologies. Compared to LDMOS, GaN-on-SiC offers significant improvements in 5G technology, such as superior thermal characteristics, and is more efficient for higher-frequency 5G applications.

Implications for 5g smartphones

In spite of these trends, RF GaAs devices still have a role to play in 5G and WiFi 6 handsets. Sales due to these are projected to grow from about USD2.8 billion in 2019 to over USD3.6 billion in 2025. The handset market is the big driver for GaAs devices, with power amplifier (PA) content increasing per phone. In general, 4G LTE cellular phones need to span multiple frequency bands, with an increasing number of PAs per phone. The 5G demand for PAs is at least a factor of two more than for 4G. Adding to that, the stringent requirements for linearity and power make GaAs the material of choice for PAs in the RF front-end module (FEM). Even though CMOS has lower cost per chip, it will not necessarily have an advantage over GaAs when it comes to modules and performance.

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5G smartphones will also need improved charging capabilities. While earlier phones could charge at 10A, recently introduced 5G types typically require chargers with capability closer to 45A. This can be handled by USB-C charging, using the latest PD 3.0 specification for programmable power supplies (PPS). Along with the necessary power capacity, it offers the most efficient charging solution on the market.

Device example

Delta Telecom produces rectifiers for use in 5G telecom networks around the world, and achieves efficiencies to 98 %, with power densities of 56.8 W/in3. They use CoolGAN 600V e-mode HEMT GaN devices from Infineon Technologies. These are qualified according to JEDEC standards, offering lifetimes beyond 15 years. The devices’ GaN technology allows energy efficiency and power density levels not possible with silicon devices, along with high reliability .