This year’s event was definitely the real ‘kick-off’ point for the wide bandgap semiconductors and especially the ones based on Gallium Nitride (GaN). It was also a symbolic milestone for a technology called ‘Digital Power’ that emerged in 2003 as a promising technology. As it was for digital power 15 years ago, GaN started its journey five years ago, and following a similar path is moving gradually from a ‘technical curiosity’ to a ‘commercial product’. Both Digital Power and GaN are technologies that have been highly debated and challenged when introduced to the market and it is interesting to link the two in this way, especially when the outcome of combining the best of these two technologies will result in truly outstanding commercial products.
From scepticism to game changer
Ten years ago when GaN pioneers presented the concept of industrializing a disruptive technology aimed at offering a more efficient Gallium Nitride based alternative to super-junction MOSFETs, it attracted a lot of opinions and strong statements: “It will never fly”! As it has been for the digital power, the journey from ‘garage development’ to commercial products has been full of frustration, tears and deceptions, though the perseverance and strong believes in the technology have brought it to a successful state.
GaN high-electron mobility transistors (HEMT) have very interesting intrinsic behaviour patterns, delivering superior switching performance and able to offer unprecedented levels of performance compared to conventional MOSFETs. In terms of intrinsic performance, having a very low charge gate, zero reverse recovery and flat output capacitance, GaN has everything that power designers dreamt of for decades to improve performance, decrease size and reach the mythical 99.99 % efficiency.
One example of a benefit of GaN transistors is the die size, which is much smaller than conventional MOSFETs as illustrated in figure 1. The graph compares the normalized area of a chip versus the voltage rating of the best MOSFETs in blue, with the latest generation of GaN FETs. The separation in the die size ‘Figure-of-Merit’ between silicon and GaN FETs is growing rapidly. It now sits at 16 times at 200V and four times at 100V - and we may not have reached the limits yet. This opens the door for power designers to create higher integration and products that will literally amaze us with their performance levels. So much so in fact, it looks like we have truly entered a game-changing era!