Design Consideration for Characterization and Study of Dynamic on State Resistance of GaN Devices

On state resistance (R
_DSON
) of GaN devices is not constant like Si devices. The RDSON of GaN devices exhibits a dynamic behavior and can be much larger than the static RDSON. This dynamic behavior depends on various factors and device-to-device from different manufacturers. The increased RDSON leads to increased power loss and reduces overall system efficiency which can lead to reliability concern. For the dynamic R
_DSON
characterization, Double Pulse Test (DPT) is a widely used method. To calculate R
_DSON
, real-time measurements of voltage across the Device Under Test (DUT) and current through the DUT are required. Common DUT current measurement techniques require the insertion of current sensor in the current path, which introduces additional loop inductance in the current path. In this paper inductor current measurement is used instead of DUT current for the dynamic R
_DSON
calculation. Use of the inductor current measurement in R
_DSON
calculation optimizes the switching loop by eliminating the need of direct DUT current measurement. Furthermore, different design considerations for double pulse test circuit, and dynamic RDSON characterization of two different GaN devices are presented.