GaN blossoms into full technology solution

GaN devices, both discrete and integrated, are becoming more and more available targeting an ever-increasing range of applications.

BY DR DENIS MARCON, GENERAL MANAGER, INNOSCIENCE EUROPE

NOT SO LONG AGO, gallium nitride (GaN) technology was considered to be suitable only for specific applications in RF and microwave and other specialist markets. The first and still largest commercial usage of GaN for power switching applications is to be found in compact mobile phone chargers, where the emergence of the USB-PD standard and market pressure for sleek accessories created a demand for higher power density. It could be said that the GaN industry ‘grew up’ with this market, learning how to deliver large volumes of parts. But now the GaN industry is transitioning again with the emergence of a wide variety of GaN devices, both high and low voltage and – recently – by adding integrated solutions as well as discrete HEMTs.

Figure 1: Astonishing power density specs can be achieved using GaN in both the primary and secondary PSU sides.

It’s probably worth spending a paragraph highlighting just what all the fuss is about. Simply, GaN delivers higher power, higher power density and greater efficiency with almost zero switching losses. This is mainly due to two factors. First, the accepted industry benchmark Figure of Merit, Ron Qg, is 10 times better than silicon. This means that systems can switch at a higher frequency without incurring any loss in efficiency. This gives designers the freedom to use smaller passives, which can result in reducing the overall BOM cost (more later). High efficiency also means that less heat is generated, so thermal management solutions such as heatsinks and fans can be eliminated or reduced in size.

The second aspect of GaN is that it has no body diode, and therefore the reverse recovery current is zero. This allows designers to select simpler power conversion topologies; for example, the totem pole bridgeless PFC design can be used instead of the more complex, larger BOM, dual boost bridgeless PFC circuit which would be necessary to keep efficiency high if the design was restricted to using even the best silicon MOSFETS.

In order for GaN to succeed in a wide range of application fields, industry needs a correspondingly wide range of GaN devices.