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Gallium nitride (GaN) based power electronics devices are actively being evaluated to determine if their theoretical advantages over silicon (Si) based switches can translate into improved performance of existing hardware as well as open the doors to new types of applications, such as high temperature implementations, or very high frequency power conversion. The following paper presents an overview of this activity. A brief summary about power electronics and the requirements of semiconductor devices used in this field is provided. Detailed analysis of the advantages and the challenges of using GaN devices is included along with a survey of demonstrations. This work also presents the test results from the evaluation of GaN devices from Efficient Power Conversion (EPC) and Transphorm. Included is a demonstration of EPC's devices in a high frequency, high efficiency, switched-capacitor voltage doubler. This circuit achieves an output of 480 W at a switching frequency of 893 kHz.

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Paralleling devices is an effective way to achieve higher power application while still having the convenience of using discrete devices. However, the mechanisms of potential failures and the circuit design considerations has not been thoroughly studied yet, when paralleling Gallium Nitride High Electron Mobility Transistors (GaN HEMTs) in cascode configuration. This paper presents a comprehensive study on paralleled high voltage cascode GaN HEMTs, evaluating both circuit design and device characteristic. The mechanisms of current oscillation, which occurred during the cascode GaN HEMTs parallel operation, are analyzed in detail. The Q3D tool and SPICE-based simulation model jointly quantify the sensitivity of the circuit parasitic parameters and the cascode GaN HEMTs mismatches during the paralleled operation. General design guidelines are provided in the paper as well. A group of experimental results ultimately validate the analysis toward parallel operation.

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