The Power and Evolution of GaN - Part 1

Alex Lidow, CEO and Co-founder of EPC


Part 1 of a 6 part series

Figure 3: LiDAR car

Gallium nitride(GaN)-on-silicon low voltage power devices have enabled many new applications since commercial availability began in 2010. New markets, such as light detection and ranging (LiDAR), envelope tracking, and wireless power, emerged due to the superior switching speed of GaN. These new applications have helped develop a strong supply chain, low production costs, and an enviable reliability record. All of this provides adequate incentive for the more conservative design engineers in applications, such as dc–dc converters, ac–dc converters, and automotive to start their evaluation process.

In this series, a few of the many, high volume applications taking advantage of GaN to achieve new levels of end-product differentiation will be discussed. First, it is useful to explore the factors attributing to the rapid acceleration of the adoption rate.

GaN Technology – A Proven Technology

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Figure 1: EPC FETs-and-ICs lineup

When EPC launched its first commercially available products in 2010, four key attributes leading to the success of new semiconductor technology to displace the venerable silicon power MOSFET were identified.  The first of these was ‘Does GaN technology enable significant new applications?’

Today’s commercially available eGaN® FETs and ICs are 5 to 50 times better performing than state-of-the art silicon solutions.  This large jump in performance has led to several new applications that were not possible until the availability of GaN technology. Among these new applications are LiDAR(light detection and ranging) for autonomous cars, augmented reality which enhance the gaming experience, warehouse automation that increases productivity, and airborne drones. A lesser known application made better by GaN is envelope tracking power supplies that can double the energy efficiency of RF power amplifiers used to transmit rapidly increasing amounts of voice and data communications through satellites, base stations, and cell phones. Wireless power systems using eGaN FETs and ICs are helping to eliminate power cords by providing energy wirelessly over a large surface area to simultaneously power a wide range of devices including cell phones, notebook computers, wireless speakers, smart watches, table lamps, and more.

The second attribute needed by a new technology in order to take hold asks; ‘Is it easy to use?’ GaN-based power conversion systems offer higher efficiency, increased power density, and lower overall system cost than silicon-based alternatives. As GaN continues to penetrate application designs, the surrounding ecosystem of supporting components that specifically enhance in-circuit GaN performance continues to grow. Today this ecosystem is no longer a limiting factor in GaN-based designs, and designers have a rapidly growing number of gate drivers, controllers, and passive component options to choose from. It should also be noted that the list of companies selling GaN power devices or complementary supporting components is growing almost monthly and includes companies such as GaN Systems, Navitas Semiconductor, Texas Instruments, Panasonic, and On Semiconductor. 

As a third attribute, customers ask a new technology; ‘Is it VERY cost effective Design engineers may delight in the performance of a system using GaN instead of a power MOSFET, but unless the new technology is cost competitive…and even less expensive, there will be resistance from purchasing departments. In May 2015, EPC’s latest generation of product crossed over the price curve with MOSFETs of similar voltage and on-resistance. There were three main reasons for this change; 1) volumes had reached the point where economies of scale kicked-in, 2) GaN transistor die sizes are three to five times smaller than MOSFETs, and 3) EPC’s eGaN transistors are provided in a chip-scale format, eliminating the costs associated with packaging -- costs that add 50% or more to the cost of a silicon MOSFET.

The fourth attribute; ‘Is it reliable?’ There has been an enormous amount of reliability testing performed on GaN devices from several manufacturers, including EPC, GaN Systems, Panasonic, and Transphorm. It has been shown that GaN devices can not only pass standard JEDEC testing originally designed for silicon-based power MOSFETs, but devices from both Transphorm and Efficient Power Conversion have passed the more-stringent automotive qualification requirements (AEC Q101). Moreover, EPC’s eGaN transistors and integrated circuits with chip-scale packaging do not have any of the reliability failure mechanisms brought on with traditional MOSFET packaging. As evidence of basic reliability in actual real-world applications, EPC has tracked over 30 billion hours in customer applications over the past four years…with only three device failures. This is a record unmatched by even the silicon power MOSFET!

GaN Technology – Increasing Mainstream Applications

GaN has met the requirements to displace silicon solutions: it enables new applications, and these new applications have helped to develop a robust ecosystem, lowered production costs, and created an enviable reliability record. How GaN technology is being put into action in volume applications will be discussed over the course of this series. 

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Figure 2: EPC9205

The first traditional application addressed in this series, the reader will be shown how to build the smallest and most efficient 48 V – 12 V DC/DC converter suitable for high-performance computing and telecommunication applications using eGaN FETs and ICs.  This article will show how a GaN-based power module, configured as a synchronous buck converter, yields a power density of 1400 W/in3 when operating at 48 V input, 12 V output and a 10 A load. This design is capable of producing an output voltage ranging from 5 V to 12 V and delivering 14 A per phase of output current.  This solution is ideal for high density computing applications such as multi-user gaming systems, autonomous cars, artificial intelligence, and cryptocurrency mining.

In a later article, an ultra-fast high-power GaN-based laser driver commonly used in LiDAR systems will be analyzed. These LiDAR systems are used in applications such as autonomous cars, drones, and robots as well as home and industrial security systems.  These applications need high current, narrow pulses to achieve the necessary distance resolution – pulses as short as a few nanoseconds or even less. The extremely high performance of GaN and the ultra-low inductance of the chip-scale package make eGaN FETs and ICs the ideal switches for pulsed laser drivers.

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Figure 3: LiDAR car

Further in the series, how GaN is transforming medicine by bringing precision control to surgical robots will be examined.  Robotic-assisted surgery improves surgical precision capability and, in many cases, requires minimal invasive access to the patient.   Robotic surgery involves control of multiple compact surgical arms using the ultra-reliable, high-performance brushless (BLDC) class of motor drive systems.   These surgical systems require a motor with high efficiency, minimal vibration, and precision control. eGaN FETs and ICs offer higher efficiency and precision motor control in a smaller solution than equivalent, traditional MOSFET solutions and are ideal for this application.

In a later article, a low cost, high efficiency 12 V – 1 V Point-of-Load (POL) converter design will be presented. This article will show how a GaN-based power module, configured as a synchronous buck converter, can yield a power density of 1000 W/in3 capable of delivering 12 A per phase. This high level of power density is ideal for high-performance computing, cryptocurrency mining, and telecommunication applications.

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Figure 4: EPC9204

The final article in this series will take a look ahead to where GaN technology is going.  It is important to remember that, while GaN has made many advancements in just a few short years, it is still far from its theoretical performance limitations and profound improvements can still be made in basic device performance. The greatest opportunity, however, for GaN to impact the performance of power conversion systems comes from the intrinsic ability to integrate both power-level and signal-level devices on the same substrate. In time, the performance and cost advantages of GaN-on-silicon will result in a majority of applications currently using silicon MOSFETs converting to the smaller, faster, cheaper, and more reliable GaN technology.

EPC (Efficient Power Conversion)