How to easily incorporate GaN devices in your design? The answer is detailed~~

Gallium nitride (GaN) and silicon carbide (SiC) are known as the "two heroes" in the third-generation semiconductor industry. Among them, SiC has outstanding advantages in high-voltage and high-current applications, and has been in the limelight in power electronics fields such as new energy vehicles and renewable energy in recent years; while GaN, with its excellent breakdown field strength characteristics and electron saturation speed, provides excellent low on-resistance and high-speed switching (high-frequency operation) performance, and performs well in 100~600V medium-voltage applications.

(Image source: ROHM Semiconductor)

It is not difficult to see that since the application scope of GaN has more intersections with traditional Si-based devices, its market prospects are broader and it is easier to find a breakthrough point in the replacement and upgrading of Si-based devices. This is indeed the case. After 2020, with the application in fast charging adapters, GaN devices have successfully become popular, which also proves that its excellent characteristics such as low on-resistance and high-speed switching have significant competitive advantages in high-power, high-efficiency and miniaturized product design.

This success in the consumer sector has also become a catalyst for the rapid penetration of GaN devices into industrial and data center applications, and the GaN market size has also grown rapidly. According to Yole Group's forecast, from 2022 to 2028, the GaN power device market size will grow from US$184.9 million to US$2.04 billion, with a compound annual growth rate of 49%.

With such a hot market, powerful semiconductor manufacturers will naturally not miss it, so the "explosive smell" in the GaN field has become increasingly intense in recent years. To win in this competition, semiconductor manufacturers need to work hard in two aspects:

In the field of GaN devices, ROHM Semiconductor 's (hereinafter referred to as ROHM) EcoGaN™ series product portfolio is a successful example. This series includes not only high-performance GaN switch products, but also innovative devices designed to simplify GaN application development, providing value to customers in helping terminal products to further save energy and miniaturize.

Figure 2: ROHM EcoGaN™ GaN product logo

(Image source: ROHM Semiconductor)

GaN HEMT is the mainstream architecture of GaN switching devices. It is a field effect transistor that uses high-mobility two-dimensional electron gas induced at the semiconductor heterojunction as a channel. The current between the drain and source of the device flows laterally through the two-dimensional electron gas channel at high speed, thereby achieving excellent switching characteristics. Based on the excellent physical properties of GaN, the thin drift layer of GaN HEMT can achieve a withstand voltage of 650V and very low on-resistance to meet the requirements of miniaturized power system design in medium power, medium voltage and high frequency applications.

Figure 3: Structure of an enhancement-mode GaN-HEMT

(Image source: ROHM Semiconductor)

Compared with some other players in the GaN field, ROHM's GaN HEMT products seem to have only been on the market for a short time, but in fact the technology behind them is very profound.

As early as 2006, ROHM began to develop GaN products and successfully applied the basic epitaxial and growth technologies developed for reliable mass production of LED products to GaN HEMT products, solving the problem of growing high-quality GaN epitaxial layers based on GaN-on-Si substrates.

In 2021, ROHM first launched a 150V GaN HEMT device with an 8V gate-source rated voltage, successfully entering the GaN device market. Then in 2022, it launched the first GaN HEMT with a withstand voltage of 650V. With its special structure, ROHM has increased the gate-source rated voltage of GaN HEMT from the traditional 6V to 8V, which has improved the design margin and reliability of the GaN device power circuit and established its competitive advantage. In April 2023, ROHM's 650V GaN HEMT was mass-produced, thus forming two main discrete GaN switching device product series of 150V and 650V.

GNP1 EcoGaN™ 650V GaN FET is a representative product. Its low on-resistance and high-speed switching characteristics can greatly improve power conversion efficiency and reduce system cabinet size. At the same time, the device's built-in ESD protection function and excellent heat dissipation performance can also help improve system reliability and design flexibility.

In summary, this GaN HEMT has three significant advantages when creating high switching frequency and high-density power converters:

• Faster switching speeds: Helps achieve fast response, improve overall system performance and enable advanced features.

• Higher voltage capability: 650V voltage rating ensures robustness and resilience, making it ideal for medium and high voltage applications such as power supplies, motor control and electric vehicle systems.

• Enhanced reliability: Built with advanced GaN technology, these devices offer improved thermal management, which helps improve device reliability and extend lifetime.

Figure 4: GNP1 EcoGaN™ 650V GaN FET

(Image source: ROHM Semiconductor)

Although GaN HEMT has many advantages in switching performance compared to Si MOSFET, as a new type of device, it still encounters many pain points in actual application development, and gate drive is one of the pain points.

Specifically, there are two main challenges in GaN HEMT gate driving: first, the driving voltage of GaN HEMT is low (usually 1.5 to 1.8V), which has the risk of false start-up; second, the gate withstand voltage of GaN HEMT is low (about 6V), and the gate is easily damaged. Therefore, a specially optimized gate driver is required to be used with GaN HEMT to achieve a complete solution.

This "added" gate driver will not only increase the number and cost of the system BOM, but also increase the complexity of the design because of additional factors such as the influence of parasitic components, becoming a technical threshold for developers when using GaN HEMT.

Figure 5: Gate drive challenges facing GaN HEMTs

(Image source: ROHM Semiconductor)

To help developers easily overcome the technical threshold of GaN HEMT gate drive, ROHM has combined its professional experience and technical advantages in power and analog to develop the Nano Cap™ 650V GaN HEMT power stage IC - BM3G0xxMUV-LB series, which integrates 650V GaN HEMT, gate driver and related peripheral components. While simplifying design and improving development efficiency, it also releases the advantages of GaN HEMT to a greater extent.

Figure 6: Nano Cap™ 650V GaN HEMT power stage IC

(Image source: ROHM Semiconductor)

Figure 7: Nano Cap™ 650V GaN HEMT power stage IC block diagram

(Image source: ROHM Semiconductor)

The core advantages of this GaN HEMT power stage IC are reflected in three aspects:

• Simplifying GaN device system development: Integrating 650V GaN HEMTs, dedicated gate drivers, added functions and peripheral components in an integrated package makes GaN device application development easier.

• Easy replacement of Si-based solutions: This power stage IC has a wide driving voltage range (2.5~30V), a typical startup time of 15μs, and a transmission delay of 11~15ns, making it an ideal "drop-in" for existing Si-based solutions.

• Lower loss, smaller size: Compared with conventional solutions, the GaN HEMT power stage IC reduces power loss by about 20%, reduces the number of external components required from 8 to 1, and significantly improves performance.

In a nutshell: Nano Cap™ 650V GaN HEMT power stage IC can meet many requirements of power electronic systems in terms of miniaturization, simplified design, reliability, low loss, etc., greatly lowering the technical threshold for GaN application development. It is an ideal solution for industrial equipment, power supplies, bridge topologies, adapters and other applications to upgrade to third-generation semiconductor technology.

It is not difficult to see that ROHM's strategy in the GaN field is very clear: on the one hand, it continues to create high-quality discrete GaN switch devices to enrich its product portfolio; on the other hand, through functional integration, it reduces the difficulty of GaN system application development and accelerates the large-scale commercialization of GaN.

It has been proven that this strategy is very successful; therefore, ROHM will continue to carry out this successful strategy in the future.

Specifically, in terms of GaN discrete devices, ROHM will continue to expand its two existing main products, launching second/third generation 150V withstand voltage products, 650V withstand voltage products using new packages, etc.; in terms of integrated innovative solutions, ROHM plans to mass-produce products equipped with pseudo-resonant AC-DC circuits or power factor improvement circuits, as well as half-bridge circuits in 2024; and plans to mass-produce products that integrate GaN HEMT, gate driver IC, and control IC in the same package before 2026.

Figure 9: EcoGaN ^TM GaN product roadmap

(Image source: ROHM Semiconductor)

In short, ROHM is working hard to make GaN devices more rapidly "conquer" the field of power electronics, and they will eventually become ubiquitous.

If you also want to easily incorporate GaN devices in your design, don’t miss the following ROHM products and solutions~~