Evaluation of the switching characteristics of a gallium-nitride transistor

Gallium-nitride (GaN) technology for power conversion is maturing, with a growing need to evaluate the capabilities of GaN devices in high switching frequency and elevated ambient temperature operation. These capabilities may particularly benefit systems constrained by strict EMI standards, due to the possibility of significant size and weight reduction. An inductive load tester circuit has been developed for switching characterization of a GaN transistor (EPC1010) and a paired silicon diode (SBR10U200P5). Maximum measured switching speeds for hard switching turn-on and turn-off transitions were dv/dt (on) = 4 V/ns, di/dt (on) = 4.5 A/ns, and dv/dt (off) = 18 V/ns, di/dt (off) = 5 A/ns respectively. Total measured switching energy loss was E tot = 40 μJ under 100 V supply voltage and 15 A load current conditions, with little change with increase of transistor junction temperature from 25 °C to 100 °C. Zero-voltage switching reduced loss to only E tot = 6 μJ, thus enabling high switching frequency operation. As the switching pair of a silicon diode and an EPC1010 is not suitable in hard switching mode and high switching frequency operation due to high switching loss of the turn-on process, another tester was built. Here, two EPC1010 devices were used in a phase-leg configuration. The fastest switching speeds were dv/dt (on) = 21 V/ns, di/dt (on) = 9 A/ns, and dv/dt (off) = 20 V/ns, di/dt (off) = 2 A/ns respectively. Total measured switching energy loss was E tot = 11 μJ, under 100 V supply voltage and 15 A load current conditions.