GaN Talk Blog

Recent advancements in gallium nitride (GaN) power devices demonstrate a substantial expansion of their operational range into low-voltage applications under 40 V. Silicon MOSFETs have historically dominated this voltage range due to their good conduction performance, well-understood manufacturing processes, and proven reliability.

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Sustainable energy is crucial in today’s world, and GaN Power ICs can help your company get there. Find out more here from EPC.

Until recently, to achieve high-quality sound from an audio amplifier cost thousands of dollars and relied on a large, heavy, power-hungry class-A amplifier. Now, the advent of gallium nitride FETs and ICs is ushering the age of high quality, lower cost class-D audio amplifiers. 

Distortion Performance Issues Lowered with GaN

Historically, meeting the required distortion performance targets (THD+N, TIM and IM) for high-quality audio, class-D amplifiers had to resort to incorporating large amounts of feedback circuitry to compensate for poor open-loop performance. The source of this distortion was the silicon power MOSFET.

GaN-based solutions coupled with digital control and high-performance magnetics can increase efficiency, shrink the size, and reduce system costs for high density computing applications like ultra-thin laptops and high-end gaming systems.

As computers, displays, smart phones and other consumer electronics systems have become thinner and more powerful over the past decade, there is increasing demand for addressing the challenge of thinner solutions while extracting more power out of limited space.

The multilevel converter is an exceptional candidate to shrink the size of the magnetic components and achieve high efficiency in a compact solution. Leveraging the advantages of eGaN^® FETs, such as small size and low loss, further enhances the performance of a multilevel solution. This blog will evaluate the EPC9148, a 48 V to 20 V, 250 W three-level converter using eGaN FETs and digital control which achieves a peak total system efficiency of 97.8% and only 4.1 mm component height.

Brick DC-DC converters are widely used in data center, telecommunication and automotive applications, converting a nominal 48 V bus to (or from) a nominal 12 V bus. Advances in GaN integrated circuit (IC) technology have enabled the integration of the half bridge and gate drivers, resulting in a single chip solution that simplifies layout, minimizes area, and reduces cost.

This application note discusses the design of a digitally controlled bi-directional 1/16th brick converter using the integrated GaN power stage for 48 V-to-12 V application, with up to 300 W output power, and peak efficiency of 95%.

The standard dimension of the 1/16th brick converter is 33 x 22.9 mm (1.3 x 0.9 inch). The height limit for this design is set to 10 mm (0.4 inch).

Acknowledgement - This application note and associated hardware was developed in collaboration with Semiconductor Power Electronics Center (SPEC) at University of Texas at Austin.

Motivation

The expansion of applications such as cloud computing, wearables, machine learning, autonomous driving, and IoT drive us towards an even more data-intensive world, increasing demands on data centers and power consumption [1, 2]. The importance of efficiency, power density, and cost of the AC to DC switching power supply is driving innovative solutions that eGaN FETs can solve to yield ultra-high efficiency power factor correction (PFC) front-end rectifier solutions that are the focus of this how-to-application note.

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.

Beyond just performance and cost improvement, the most significant opportunity for GaN technology to impact the power conversion market comes from its intrinsic ability to integrate multiple devices on the same substrate. GaN technology, as opposed to standard silicon IC technology, allows designers to implement monolithic power systems on a single chip in a more straightforward and cost-effective way.

Today, the most common building block used in power conversion is the half bridge. In 2014, EPC introduced a family of integrated half-bridge devices which became the starting point for the journey towards a power system-on-a-chip. This trend was expanded with the introduction of the EPC2107 and EPC2108, which integrated half bridges with integrated synchronous bootstrap. In 2018 we further continued the integration path with the introduction of eGaN ICs combining gate drivers with high-frequency GaN FETs in a single chip for improved efficiency, reduced size, and lower cost. Now, the ePower™ Stage IC family redefines power conversion by integrating all functions in a single GaN-on-Si integrated circuit at higher voltages and higher frequency levels beyond the reach of silicon.

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.