Parasitic Elements Extraction of the GaN HEMT Packaged Power Transistors based on S-parameter measurements

This paper presents a complete methodology based on an accurate S-parameters calibration procedure to determine parasitic resistances, inductances, and capacitances of a packaged GaN power transistor. Results show the possibility to extract very low device parasitics which may influence switching mechanisms in power converters. The accuracy of the S parameter characterization is verified on a SiC power MOSFET. Good agreement is found between extracted values and technical data provided in the literature. The extracted linear model of the tested GaN HEMT is simulated in the frequency domain using an S-parameters circuit simulator. The excellent match between the measurement and simulation indicates a high accuracy of the S-parameter extraction technique. The GaN HEMT parasitic elements are obtained from the S-parameters measured using a vector network analyzer and then converted to the impedance (Z) parameters. These parameters, through detailed network analysis, provide more accurate values of the internal parasitic inductances than the commonly used LCR meter measurement technique. The method has the capability to be applied to any packaged GaN power transistor fabricated by different manufacturers.