In this paper, we present a comprehensive reviewand discussion of the state-of-the-art device technology and application development of GaN-on-Si power electronics. Several device technologies for realizing normally off operation that is highly desirable for power switching applications are presented. In addition, the examples of circuit applications that can greatly benefit from the superior performance of GaN power devices are demonstrated. Comparisonwith other competingpower device technology, such as Si superjunction-MOSFET and SiC MOSFET, is also presented and analyzed. Critical issues for commercialization of GaN-on-Si power devices are discussed with regard to cost, reliability, and ease of use.

GaN-on-Si Power Technology: Devices and Applications

Gallium nitride (GaN) power devices are an emerging technology that have only recently become available commercially. This new technology enables the design of converters at higher frequencies and efficiencies than those achievable with conventional Si devices. This paper reviews the characteristics and commercial status of both vertical and lateral GaN power devices, providing the background necessary to understand the significance of these recent developments. In addition, the challenges encountered in GaN-based converter design are considered, such as the consequences of faster switching on gate driver design and board layout. Other issues include the unique reverse conduction behavior, dynamic $R_{\mathrm {{ds}},\mathrm {{on}}}$ , breakdown mechanisms, thermal design, device availability, and reliability qualification. This review will help prepare the reader to effectively design GaN-based converters, as these devices become increasingly available on a commercial scale.

Review of Commercial GaN Power Devices and GaN-Based Converter Design Challenges

This timely second edition has been substantially expanded to keep students and practicing power conversion engineers ahead of the learning curve in GaN technology advancements. Acknowledging that GaN transistors are not one-to-one replacements for the current MOSFET technology, this book serves as a practical guide for understanding basic GaN transistor construction, characteristics, and applications. Included are discussions on the fundamental physics of these power semiconductors, layout and other circuit design considerations, as well as specific application examples demonstrating design techniques when employing GaN devices.

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GaN Transistors for Efficient Power Conversion

Gallium nitride high electron mobility transistor (GaN HEMT) has matured dramatically over the last few years. A progressively larger number of GaN devices have been manufactured for in field applications ranging from low power voltage regulators to high power infrastructure base-stations. Compared to the state-of-the-art silicon MOSFET, GaN HEMT has a much better figure of merit and shows potential for high-frequency applications. The first generation of 600 V GaN HEMT is intrinsically normally on device. To easily apply normally on GaN HEMT in circuit design, a low-voltage silicon MOSFET is in series to drive the GaN HEMT, which is well known as cascode structure. This paper studies the characteristics and operation principles of a 600 V cascode GaN HEMT. Evaluations of the cascode GaN HEMT performance based on buck converter at hard-switching and soft-switching conditions are presented in detail. Experimental results prove that the cascode GaN HEMT is superior to the silicon MOSFET, but it still needs soft-switching in high-frequency operation due to considerable package and layout parasitic inductors and capacitors. The cascode GaN HEMT is then applied to a 1 MHz 300 W 400 V/12 V LLC converter. A comparison of experimental results with a state-of-the-art silicon MOSFET is provided to validate the advantages of the GaN HEMT.

Evaluation and Application of 600 V GaN HEMT in Cascode Structure

The introduction of enhancement-mode gallium-nitride-based power devices such as the eGaN FET offers the potential to achieve higher efficiencies and higher switching frequencies than possible with silicon MOSFETs. With the improvements in switching performance and low parasitic packaging provided by eGaN FETs, the printed circuit board (PCB) layout becomes critical to converter performance. This paper will study the effect of PCB layout parasitic inductance on efficiency and peak device voltage stress for an eGaN FET-based point of load (POL) converter operating at a switching frequency of 1 MHz, an input voltage range of 12-28 V, an output voltage of 1.2 V, and an output current up to 20 A. This paper will also compare the parasitic inductances of conventional PCB layouts and propose an improved PCB design, providing a 40% decrease in parasitic inductance over the best conventional PCB design.

Understanding the Effect of PCB Layout on Circuit Performance in a High-Frequency Gallium-Nitride-Based Point of Load Converter

The introduction of enhancement mode gallium nitride based power devices such as the eGaN®FET offers the potential to achieve higher efficiencies and higher switching frequencies than possible with Silicon MOSFETs. With the improvements in switching performance and low parasitic packaging provided by eGaN FETs, the PCB layout becomes critical to converter performance. This paper will study the effect of PCB layout parasitic inductance on efficiency and peak device voltage stress for an eGaN FET based point of load (POL) converter operating at a switching frequency of 1 MHz, an input voltage range of 12-28 V, an output voltage of 1.2 V, and an output current up to 20 A. This work will also compare the parasitic inductances of conventional PCB layouts and propose an improved PCB design providing a 40% decrease in parasitic inductance over the best conventional PCB design.

Understanding the effect of PCB layout on circuit performance in a high frequency gallium nitride based point of load converter

The emergence of gallium nitride (GaN)-based power devices offers the potential to achieve higher efficiencies and higher switching frequencies than possible with mature silicon (Si) power MOSFETs. In this paper, we will evaluate the ability of gallium nitride transistors to improve efficiency and output power density in high frequency resonant and soft-switching applications. To experimentally verify the benefits of replacing Si MOSFETs with enhancement mode GaN transistors (eGaNFETs) in a high frequency resonant converter, 48–12 V unregulated isolated bus converter prototypes operating at a switching frequency of 1.2 MHz and an output power of up to 400 W are compared using Si and GaN power devices.

Evaluation of Gallium Nitride Transistors in High Frequency Resonant and Soft-Switching DC–DC Converters

Integrated L-L-C-T (inductor-inductor-capacitor-transformer) technology has been the subject of intensive research over the last few years. Its application to resonant power electronic converters has been reported by many previous publications. This paper presents the application of a planar L-L-C-T module to the integration of passive module for a zero-voltage-switched asymmetrical half bridge PWM converter for application in distributed power systems. Two output transformers, two current doubler inductors, the ZVS resonant inductor and the transformer DC decoupling capacitor are integrated into a single module. The design procedure is discussed and some special considerations of the L-L-C-T module in nonresonant applications are addressed. A 1 kW 300 V-400 V input, 48 V output asymmetrical half bridge PWM converter (AHBC) employing the L-L-C-T module is constructed. A comparison of the AHBC using the integrated passive module and the same circuit using discrete components is given.

Johan Strydom

Papers

GaN Transistors for Efficient Power Conversion

Understanding the Effect of PCB Layout on Circuit Performance in a High-Frequency Gallium-Nitride-Based Point of Load Converter

Understanding the effect of PCB layout on circuit performance in a high frequency gallium nitride based point of load converter

Evaluation of Gallium Nitride Transistors in High Frequency Resonant and Soft-Switching DC–DC Converters

Design of planar integrated passive module for zero-voltage-switched asymmetrical half-bridge PWM converter