GaN-HEMT dynamic ON-state resistance characterisation and modelling

Abstract

Abstract-GaN-HEMTs suffer from trapping effects which might increase device ON-state resistance (R DS(on) ) values. Thus, dynamic R DS(on) of a commercial GaN-HEMT is characterized at different bias voltages in the paper by a proposed measurement circuit. Based on the measurement results, a behavioural model is proposed to represent device dynamic R DS(on) values, in which trapping and detrapping time constant is represented by a series of RC network. The model is simulated in PSPICE, of which the simulation results of R DS(on) values are compared and validated with the measurement when device switches in a power converter with different duty cycles and switching voltages. The results show that R DS(on) values of this device would increase due to trapping effects.

Modelling and quantification of power losses due to dynamic on-state resistance of GaN E-mode HEMT

“…However, the proposed model does not allow for different time constants for charging and discharging. The experimental results in [8] indicate that such a difference exists.…”

“…The goal of the clamping circuit is to keep the voltage at approximately the same magnitude during both on and off state while at the same time allow for accurate measurement of the on-state voltage. Several circuits for high accuracy measurement of dynamic on-resistance are suggested in the literature [4], [6], [8], [9], [10]. A comparison of the circuits is presented in [11].…”

“…Also, inductive load is closer to application for most hard switched applications. The test circuit in this work was taken from [8] since it allows for precise control of both trapping and detrapping time. The circuit employs a resistive load.…”

“…Böcker et al [9] use RC models in a detailed device model to accurately model the I-V characteristics of their in-house developed GaN HEMT. Li et al in [8] measure the dynamic on-state resistance of a commercial device and implements a model of the increased resistance by manipulating the gate voltage. In turn, the on-state resistance is changed according to the device transconductance.…”

“…The dynamic R DS,on adds a loss component which currently is not accounted for during the design phase. There are several authors who have investigated the phenomenon with operation parameters close to that in actual application [2], [3], [4], [5], [6], [7], [8]. Examples of operation parameters include bias voltage, device blocking time, current, and temperature variation.…”