Fraunhofer IAF makes first monolithic 600V GaN half bridge
The Fraunhofer Institute for Applied Solid State Physics IAF has developed the world's first 600V half-bridge GaN circuit in which all the electronic components are monolithically integrated on one chip.
The 600V class is the standard for grid-connected electrical devices, ranging from tablets and washing machines to e-bikes and electric cars.
The GaN-on-silicon circuit comprises two GaN HEMTs and two integrated freewheeling diodes. The HEMTs have a breakdown voltage of more than 600V and an on-state resistance of 120mΩ. A folded chip layout enables the DC link capacitance to be tightly connected between the supply voltage and ground. This design is described as creating an optimised power path that allows for clean, stable switching at high frequencies.Â
The circuit was demonstrated last November at the 4th IEEE Workshop on Wide Bandgap Power Devices and Applications (WiPDA 2016) in a downconverter from 400 to 200 V at a switching frequency of 3 MHz.
"A switching frequency of up to 3Â MHz allows us to achieve a much greater power density. This is very important in areas such as e-mobility, where many converters which are as efficient as possible have to be fitted in very little space," Â says Richard Reiner, research associate at Fraunhofer IAF in the Power Electronics business unit.Â
The German government has set itself the target of putting one million electric cars on the country's roads by 2020. Covering long distances without generating any emissions requires not only powerful batteries but also the development of lightweight electric cars which generate as little energy as possible.
Manufacturers need to develop efficient on-board chargers for electric vehicles which take up as little space as possible.This can only be accomplished using electronic components based on semiconductor materials such as GaN which, unlike SiC, can be grown as an epitaxial layer on cost-effective, large area silicon substrates.
Fraunhofer IAF is presenting the circuit at PCIM Europe in Nuremberg, Germany from May 16"“18, 2017.
