We present a detailed analysis of large-signal Sawyer–Tower measurements on a power GaN HEMT device in OFF-state. The measurements show hysteresis which results in an energy loss dissipated as heat in the range of sub-μJ's. We model this important phenomenon in this paper using a previously calibrated model of the same device. We propose two models, one with linear Effective Series Resistance (ESR) and another using non-linear ESR (NLESR). It is found that to model the non-linear profile of hysteretic curve from Sawyer–Tower measurements, non-linear ESR and output capacitance are needed. The similarities and differences between these two models have been explained in detail. While linear ESR is shown to be a simple model for modeling the hysteretic losses, non-linear ESR and output capacitance model the dynamics of charge imbalance that occurs during the charging and discharging processes more accurately. A detailed analysis based on recent literature suggests that 2DEG electron trapping by acceptor type traps in the underlying buffer layers are the primary cause of this charge imbalance.
- Sawyer–Tower measurements
- Power GaN HEMTs
- ASM-GaN compact model
- Hysteretic loss
- Effective Series Resistance (ESR)