GaN Breaks Through Beyond its Traditional Limits

­Welcome to the February edition of Power Systems Design. The Special Report this month is on wide bandgap materials. GaN and SiC have revolutionized the industry in terms of efficiency and power density for a wide number of power applications. However, those benefits trade off with additional complexity, and as we try to get more and more performance out of the devices, that complexity only increases. The articles in this month’s Special Report feature GaN. The first one on how devices made with the material are tackling silicon at the lower end of the voltage scale, while the other sees GaN devices pushing upward beyond their traditional limits to try take market share from SiC solutions and IGBTs at higher voltage levels.

The first article was written by Kurk Mathews, Senior Applications Manager, and Luis Onofre Lazaro, Applications Engineer from Analog Devices. Low voltage GaN DC/DC converters offer clear size and performance advantage over their silicon counterparts but require precise gate voltage control and accurate high-side gate measurements. The two authors of the piece look at different ways of taking these measurements and compare isolated probes with other commonly used techniques to find out the optimal solution and provide robust, efficient designs.

The second article in the special Report was contributed by Power Integrations and written by the company’s Kamal Varadarajan and Chris Lee. 800V and 1000V voltage rails are becoming far more common in the industry as designers try to lower currents. Recently Nvidia published an 800V architecture intended for AI data centres, which is intended to address the physical and practical limitations of traditional power distribution systems which are unable to meet the extreme power demands of modern AI workloads. The new architecture increases efficiency and thereby reduces the losses wasted as heat. As a lot of power is required to cool data centres, the less heat generated by the power delivery system, the better. SiC MOSFETs and IGBTs are traditionally used at those higher voltages, but the better efficiency of GaN would be ideal to displace them if it could be made to work above its normal limit of 650V. Power Integrations recently launched 1250V and 1700V GaN devices for these sorts of applications, but can GaN prove robust enough to survive for long periods in high temperatures? In the article, the authors detail the tests that the company undertook to prove that the answer is yes. 

In addition to the articles in the Special Report, this month’s issues will also feature articles of interest to those in the power electronics fields in our Tech Focus sections, as well as the latest news and views from the industry.