How Wide-Bandgap Technology Became Real

Kevin Parmenter, Director, Applications Engineering. TSC, America



We are now moving up the slope of enlightenment onto the plateau of productivity with wide bandgap semiconductor devices, namely silicon carbide and gallium nitride. WBG devices that complement silicon devices are now readily available in products, especially at higher voltages, and designers are pleased to use high-performance GaN devices and SiC rectifiers, IGBTs and MOSFETS in their products. But the road to mainstreaming WBG technology was rockier than expected. And perhaps it serves as a cautionary tale on setting expectations when introducing even the most promising new technologies.

Almost 10 years ago, I worked with a startup GaN company made up of known experts on process technology and semiconductor physics. GaN technology was new and its promise was amazing: fast parts meant engineers could use ten-times smaller magnetics! They would be able to switch at 5 MHz and get 99.9% efficiency! Urged on by investors, the company focused on getting devices to market as quickly as possible. By putting tomorrow’s technology in 1980s packages, they reasoned, customers could plug the new devices right into their existing designs. The idea was logical in theory, but in reality, it didn’t work.

My suggestion was to build an ecology and train the customers. Since the device-switching edge times did not lend themselves to packages with high parasitics, training engineers on PCB layout and impedance matching was necessary, and control techniques and more had to be considered and built out. This idea was received like bikers at an Amish wedding: coldly. As with any new company, the thought veering from the plan ran afoul with the investors’ quarterly profit-making schedule. Today the company is successful, but as with other WBG device startups, they probably took a longer-than-needed route to get their parts into actual products.

So why is WBG technology finally mainstreaming? Just this week I saw press releases for titanium server power supplies using GaN bridgeless totem-pole topology, and several announcements for GaN + digital control AC-DC and DC-DC power converters. The answer is that the benefits and overall value of incorporating wide bandgap technology into products have become greater than the risk involved. Also,  that pesky ecology that we argued about years ago was built out after all and, over time, the packaging (or no package at all) was able to take advantage of GaN.

The production capacity for both GaN and SiC devices is expanding rapidly. Additionally, the test equipment for measuring GaN and SiC circuits with super-fast rise times have improved greatly. Because fussy analog IC companies found it too onerous to develop the right ICs for GaN device control, designers began optimizing and programming WBG designs themselves using digital mixed-signal controllers. WBG technology in general is developing into products with complete functional modules – and even with an integrated controller.

The future is super bright and there is tremendous growth potential for WBG devices and the new products they will enable. But prepare the money people: It never happens in just one quarter.  In the words of the late great Steven Covey the law of the farm will likely be with us forever. If you have not read that, study up on it, it could save you a fortune as that law can’t be violated – many have tried.