Learn why R_DS(ON) shouldn't be your main criteria for selecting switching devices. EPC's insights reveal a more effective approach for evaluating GaN FETs.

With the rapid adoption of gallium nitride transistors and integrated circuits, designers can now accomplish the required headline marketing THD+N performance targets and reduce transient intermodulation distortion to achieve the warm subtleties and color of music intended for the optimal listening experience.

Back in 2015 Venture Beat published an article on gallium nitride chips taking over from silicon.  In that article I made the assertion that widespread adoption of gallium nitride-based power semiconductors would be possible because GaN FETs would have higher performance AND lower cost than silicon.  Yet, there is still a widespread misconception that GaN has not yet reached that milestone…that is a false myth.  In this blog post, I will attempt to dispel this myth with the caveat that this discussion is limited to devices rated at less than 400 V, as that is the application focus for EPC’s FET and IC products.

It has been more than 12 years since the first GaN-on-Si power transistors started in volume production, and in many applications, such as lidar and space electronics, adoption has been extremely rapid.  But what about other markets such as consumer products, computers, motor drives, and automotive?  Even in each of those areas GaN devices have started to appear in volume as the predicted tipping point of better performance AND lower cost is a reality.

Guest GaN Talk Blog by: Pavel Gurev, Sinftech Rus LLC

This article originally appeared in Bodo’s Power Systems April 2021

In the past few years, gallium-nitride (GaN) FETs have become more widespread in power electronics. Due to their outstanding characteristics, GaN FETs play an increasingly important role in miniaturization of the switching converters with very high-power densities exceeding 100 W / cm³ and more. The efficiency of converters based on GaN transistors can reach 99.5%. Due to the extension of the conversion frequency towards the MHz range, the magnetic components (chokes, transformers) also decrease in size significantly. However, designers face numerous challenges in implementing practical GaN transistor designs. The best family members are presented in wafer-level chip-scale package; the drivers are also quite miniature.

Rethinking the Ordinary and Overcoming Mental Biases

Motor drive applications span several markets: industrial, appliance, and automotive. A commonality that occurs regardless of market is that when a new technology is proposed, it faces resistance to its adoption; after all, it is human nature to stick with what is known and resist change.

Efficient Power Conversion (EPC) is increasing the performance distance between the aging silicon power MOSFET and eGaN transistors with 100 V ratings.  The new fifth-generation “plus” devices have about 20% lower R_DS(on) and increased DC ratings compared with the prior fifth-generation products.  This performance boost comes from the addition of a thick metal layer and a conversion from solder balls to solder bars.

Efficient Power Conversion (EPC) is doubling the performance distance between the aging silicon power MOSFET and eGaN® transistors with 200 V ratings.  The new fifth-generation devices are about half the size of the prior generation.  This performance boost comes from two main design differences, as shown in figure 1.  On the left is a cross-section of the fourth generation 200 V enhancement-mode GaN-on-Si process.  The cross-section on the right is the fifth-generation structure with reduced distance between gate and source electrodes and an added thick metal layer. These improvements, plus many others not shown, have doubled the performance of the new-generation FETs.

GaN FETs can switch significantly faster than Si MOSFETs causing many system designers to ask − how does higher switching speeds impact EMI?

This blog discusses simple mitigation techniques for consideration when designing switching converter systems using eGaN^® FETs and will show why GaN FETs generate less EMI than MOSFETs, despite their fast-switching speeds.

This post was originally published by Dr. John Glaser & Dr. David Reusch on June 13, 2016 on the Power Systems Design web site.

Comparing Dead-time Losses for eGaN FETs and Silicon MOSFETs in Synchronous Rectifiers

There have been several comparisons of eGaN FETs with silicon MOSFETs in a variety of applications, including hard-switched, soft-switched, and high-frequency power conversion. These studies have shown that eGaN FETs have large efficiency and power density advantages over silicon MOSFETs. Here we’ll focus on the use of eGaN FETs in synchronous rectifier (SR) applications and the importance of dead-time management. We show that eGaN FETs can dramatically reduce loss due to dead-time in synchronous rectifiers above and beyond the benefits of low R_DS(on)and charge.

Silicon has been around long enough. It’s time for a younger and far more fit challenger to take over semiconductor material dominance.

When I first started developing power devices 44 years ago, the “king of the hill” was the silicon power bipolar transistor.  In 1978 International Rectifier (IRF) launched power MOSFETs as a faster alternative to the slower and aging bipolar devices.  The early adopters of the power MOSFET were applications where the bipolar just was not fast enough.  The signature example for its adoption was the switching power supply for the desktop computer; first at Apple, and then at IBM.