GaN transistors are smaller, faster and more power efficient. Dialog's launch of half bridge shows that they are ready for commercialization in high-volume applications.

Gallium nitride (GaN) technology is finally catching up with the promise of faster switching speeds and higher power densities that it has been flashing for more than a decade.

GaN semiconductor devices are already in use in LEDs and power amplifiers for 4G radio base stations, and now GaN-based transistors are becoming a key enabling technology in power electronics products like adapters, power supplies, and solar inverters.

 

An example of gallium nitride. Image courtesy of Michigan Tech University.

 

Power electronics—currently dominated by power MOSFETs and IGBTs—is steadily creating space for the GaN technology that boasts higher voltage and frequency and greater resistance to temperature. That, in turn, substantially reduces energy losses in power conversion.

GaN is a wide-bandgap technology—a property that determines the level of electron mobility—and it features the highest bandgap of 3.4 eV compared to the competing technologies such as silicon carbide (SiC) and gallium arsenide (GaAs). That allows GaN transistors to withstand higher electric fields, which in turn, increases power density and makes the device smaller.

 

GaN power switches are smaller, faster and more power efficient. Image courtesy of Dialog Semiconductor.

 

Besides engineering challenges, such as low-voltage operation and thermal conductivity, the higher cost of GaN transistors has been the main hindrance in their commercial realization. But that's changing now. Efficient Power Conversion or EPC, co-founded by former International Rectifier CEO Alex Lidow, is aiming to take the GaN power transistors to the economy of scale by offering power transistors that are cost competitive with their silicon counterparts like MOSFETs.

The GaN technology stalwart is using a transistor architecture that lays all the electrical connections—source, drain, and gate—on the side of the chip so that it can be easily placed on a PCB. Another crucial factor in bringing down the price of GaN parts is the creation of smaller GaN transistors so more chips can be carved out from the wafer.

 

Dialog Enters the Fray

Dialog Semiconductor, a new kid on the GaN block, has recently announced a GaN-based 650 volt half bridge design that claims to facilitate power adapters that are smaller in size and offer higher densities compared to traditional MOSFET solutions. The chipmaker has produced the power IC on TSMC's 650 volt GaN-on-silicon process technology.

It's one of the first commercial power IC based on GaN technology that is aimed at high-volume consumer markets like computer adapters and smartphone fast-chargers. Dialog claims that its 650-volt power switches reduce power losses by up to 50 percent and boost power efficiency by up to 94 percent.

 

Dialog's SmartGan half bridge integrates 650-volt high side and low side power switches. Image courtesy of Dialog Semiconductor.

 

That enables a 45-watt adapter design to fit into the form factor of a 25-watt adapter. Moreover, Dialog's DA8801 power switch integrates functions like gate drives and level-shifting circuits to further simplify the design solution. The DA8801 power IC will be available for sampling in the fourth quarter of 2016.

Dialog's power IC for power adapters clearly points to OEMs' desire for smaller, faster and more efficient devices, and how GaN chips can facilitate these requirements. It's also a testament to the fact that GaN chips are finally turning the corner after a slow development phase.

Other notable players in the GaN semiconductor market include Cree, Infineon, Macom, NXP, Qorvo, and Transphorm.

 

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