Jim Witham, CEO, GaN Systems
GaN material offers orders of magnitude improvement in switching and conduction performance and, when produced on GaN-on-Silicon substrates, can reduce power system costs. Only diamond power semiconductors have been proposed as a superior material system to GaN, but the consensus is that we are decades away from commercial viability.
Power system engineers around the world concur that the availability of GaN transistors may be the single most important advance since the IGBT became available in the 1990s. The excitement about GaN for power applications stems from its unique material and electronic properties, which result in products with power losses cut 50-90%; system size and weight reductions of up to 75% and a decreased Bill-of-Materials cost.
Compared to silicon, GaN offers ten times higher electrical breakdown characteristics, three times the bandgap and exceptional mobility, so it’s clear that the development of devices that can make the best use of these inherent characteristics while offering ease of adoption into applications will offer significant commercial advantage.
GaN Systems’ range of GaN power transistors offer current ratings from 8A to 250A and the devices’ unique structure maximizes wafer yields and produces highly efficient power switching transistors at significantly lower cost than traditional design approaches. GaN Systems’ core IP is its Island Technology die design, GaNPX packaging technology and Drive Assist on-chip drivers.
GaN Systems’ semiconductor die are built as an array of alternating ‘islands’ of drain and source material, with the gate as a grid between the islands. This maximizes the amount of gate length in a given an area, and spreads the heat from the channel evenly over the device. This leads to substantial advantage of reduction in the size and cost of gallium nitride devices.
In order to take advantage of the Island Technology devices’ intrinsic fast switching and dense current carrying capability, the company has designed proprietary packaging, GaNPX,which has minimal inductance and superior thermal resistance, with no wire bonds. In addition, GaN Systems uses on-chip drivers, which simplify circuit design and solve the drive issues while improving the switching speed. GaN Systems’ products use standard, off-the-shelf driver electronics and address reliability and performance issues such as electro-migration and debiasing.
There are a number of Application Notes on GaN Systems website, covering the basic principles of driver design, a reference driver design for a 650VGaN E-HEMT designed for a double pulse testing board, and a thermal analysis of GaN Systems’ GS66508P E-mode GaN on Si, 34A, 41mΩ power switch, together with diagrams and further explanation of how heat is dissipated by the GaNPX packaging design. The second part of this Application Note looks at the key PCB factors to consider when designing with GaNPX devices.