D27.1 - Characterization Technique for Extracting Parasitic Inductances of a Bidirectional Single GaN Four Quadrant Switch with Ferrite Bead Gate Lead Using Two-Port S-Parameters Measurements
This paper presents a characterization approach for accurately extracting the parasitic inductances, capacitances, and resistances of a bidirectional Four Quadrant Switch (FQS) based on Gallium Nitride (GaN) HEMT technology. The method uses the Transphorm TP65F060WS device (650 V GaN FQS) with integrated ferrite bead gate leads as a case study. A multi-configuration two-port S-parameter measurement scheme is proposed, explicitly accounting for the equivalent impedance of internal GaN transistors and the ferrite bead effects. This approach avoids reliance on self-resonant frequency (SRF) formulas for inductance and instead separates real and imaginary parts of the impedance to extract parasitics with greater accuracy. Experimental validation on three FQS samples shows high repeatability and good correlation with manufacturer capacitance values, while revealing deviations up to 25% in inductance due to ferrite bead tolerances. These results enable more accurate high-frequency device models for simulation and higher design optimization.
