Calibration Robustness and Cross-Device Transferability of Four Temperature-Sensitive Electrical Parameters in Enhancement-Mode GaN HEMTs

Abstract

Reliable temperature estimation in GaN high-electron-mobility transistors requires temperature-sensitive electrical parameters (TSEPs) that combine sufficient sensitivity with stable calibration behavior. This study compares on-state resistance (Rds(on)), threshold voltage (Vth), reverse-conduction voltage (Vsd), and gate-source voltage (Vgs) using three nominally identical 650 V enhancement-mode GaN HEMTs at three reference temperatures of 25, 50, and 75 °C. Each TSEP was repeatedly measured at each reference temperature, and the median value of the repeated measurements was used for calibration. Calibration performance was primarily assessed using temperature sensitivity, linearity, short-term repeatability, cross-device consistency, and leave-one-device-out calibration transferability, while a limited leave-one-temperature-out analysis was retained only as an additional internal-consistency check. Rds(on) showed a mean K-factor magnitude of 0.247 mΩ/°C, a mean R2 of 0.9974, and a K-factor coefficient of variation of 1.60%. Vgs provided the highest voltage-domain sensitivity, with a mean K-factor magnitude of 2.053 mV/°C, a mean R2 of 0.9980, and a coefficient of variation of 1.49%, whereas Vth and Vsd exhibited K-factor coefficients of variation of 5.93% and 46.11%, respectively, with the latter showing pronounced cross-device variation. The leave-one-device-out analysis yielded transfer RMSEs of 5.600 °C for Rds(on) and 6.324 °C for Vgs, substantially lower than 55.368 °C for Vth and 94.631 °C for Vsd, demonstrating that cross-device slope consistency and calibration transferability are related but distinct characteristics. These results demonstrate that robust TSEP selection should consider repeatability, cross-device consistency, and calibration transferability in addition to sensitivity and linearity.