For the GaN single chip, the team at Fraunhofer Institute for Applied Solid State Physics IAF in Freiburg combined current and temperature sensors, 600V power transistors with intrinsic flyback diodes and gate drivers.
Compared to conventional voltage converters, the new circuit not only enables higher switching frequencies and thus a higher power density, but at the same time fast and accurate condition monitoring directly in the chip. This is important because the increased switching frequency of GaN-based power electronics enables very compact designs, but also leads to stricter requirements with regard to monitoring and control. "Therefore, sensor technology integrated in the chip is a great advantage," said Stefan Mönch, researcher at Fraunhofer IAF and part of the GaNIAL research project.
The integrated current sensor now enables the non-reactive measurement of the transistor current for control and short-circuit protection and saves space compared to conventional external current sensors. The integrated temperature sensor enables direct measurement of the temperature of the power transistor and thus maps this thermally critical point much more accurately and quickly than previous external sensors, as the distance and resulting temperature difference between sensor and measuring point is eliminated by the monolithic integration.
"The monolithically integrated GaN power electronics with sensor technology and control thus saves chip space, reduces the effort required for assembly technology and increases reliability. This is crucial for applications in which many small and efficient systems have to be installed in a small space, such as electromobility," said Mönch, who designed the 4 x 3 mm² GaN chip.