Utilizing GaN transistors in 48V communications DC-DC converter design

December 06, 2016 // By Di Chen and Jason Xu, GaN Systems
As the world’s demand for data increases seemingly out of control, a real problem occurs in the data communications systems that have to handle this traffic.

Datacentres and base stations, filled with communications processing and storage handling, have already stretched their power infrastructure, cooling, and energy storage to their limits. However, as the data traffic continues to grow, higher density communications and data processing boards are installed, drawing even more power. In 2012, communications power consumptions of networks and datacentres added up to 35% of the overall electricity use in the ICT sector (Figure 1). By 2017, networks and datacentres will use 50% of the sector’s electricity, and it will continue to grow.

 

 

 

 

 

 

 

Figure 1. Worldwide electricity consumption for the ICT sector: significantly increasing power requirements in the network is forcing the communications industry to rethink its power solutions. (2013, Emerging Trends in Electricity Consumption for Consumer ICT)

 

 

One solution to this problem is to re-architect datacentre systems from distributing 12V power along the backplane to distributing 48V on the backplane. In March 2016, in the USA, Google announced that it will join the Open Compute Project, and contribute its knowledge and experience (since 2012) of utilizing a 48V distributed power system. Though this helps to solve one problem, it creates another: How do the power designers of the communications and data processing cards increase the efficiency, decrease the size and increase the power levels of their DC-DC converters, provided from 48V?

 

In today’s architectures, using 12V backplanes, the industry is able to use 40V MOSFETs with very good figure of merit (FOM) characteristics to be able to switch at high frequency, deliver high efficiency, and high power density. Using a 48V backplane forces DC-DC designers to use 100V MOSFETs, which have significantly higher FOM values [lower is better] and therefore are inherently less efficient. 100V enhancement mode GaN devices, however, are able to meet the challenges of DC-DC designers by delivering a very high efficiency, high frequency solution, as shown by comparing the FOM values