Accurate Measurement of Dynamic on-State Resistances of GaN Devices Under Reverse and Forward Conduction in High Frequency Power Converter

Abstract

Because of trapped charges in GaN transistor structure, device dynamic ON-state resistance R DSon is increased when it is operated in high frequency switched power converters, in which device is possibly operated by zero voltage switching (ZVS) to reduce its turn-ON switching losses. When GaN transistor finishes ZVS during one switching period, device has been operated under both reverse and forward conduction. Therefore its dynamic R DSon under both conduction modes needs to be carefully measured to understand device power losses. For this reason, a measurement circuit with simple structure and fast dynamic response is proposed to characterize device reverse and forward R DSon. In order to improve measurement sensitivity when device switches at high frequency, a trapezoidal current mode is proposed to measure device R DSon under almost constant current, which resolves measurement sensitivity issues caused by unavoidable measurement circuit parasitic inductance and measurement probes deskew in conventional device characterization method by triangle current mode. Proposed measurement circuit and measurement method is then validated by first characterizing a SiC-MOSFET with constant R DSon. Then, the comparison on GaN-HEMT dynamic R DSon measurement results demonstrates the improved accuracy of proposed trapezoidal current mode over conventional triangle current mode when device switches at 1 MHz.

A GaN-HEMT Compact Model Including Dynamic RDSon Effect for Power Electronics Converters

“…. More details on the measurement accuracy of the proposed measurement circuit can be found in our previous publication [28].…”

“…The advantages of TZCM are that (1) all four GaN-HEMTs can be operated under ZVS soft switching to reduce switching losses and (2) the dynamic R DSon value can be measured under constant current amplitude. Measurement error due to parasitic inductance and probe deskew on measurement results can be eliminated [28].…”

Accurate ON-State Resistance Extraction for Online Condition Monitoring of Semiconductor Devices Under Noisy Conditions

“…However, even though the presence of noise and offsets are reported, no suitable methods for mitigating their effect in an online setup are suggested. In [16], an estimation error of 2.9% is reported, however, the estimations are conducted under constant load, and under low-noise conditions. Similarly, in [24], online measurement of V-I curves have been compared to curve-traced measurements, however, they have shown that at nominal voltages and currents, the switching noise significantly distorts the ON-state voltage measurements.…”

A Novel ON-State Resistance Estimation Technique for Online Condition Monitoring of Semiconductor Devices Under Noisy Conditions

“…Consequently, in order to confidently detect aging, or to precisely estimate the junction temperature, accurate estimation of the ON-state resistance is required. The ON-state resistance is typically extracted from the ON-state voltage measurements, and load current [8], [15], [16]. A multitude of considerations are needed for accurate measurement of the ON-state voltage.…”

“…In [16], [21]- [23], depletion mode MOSFETs (DM-MOSFETs) are used for protecting the measurement circuit from the OFF-state voltage. This design is shown to also have a high bandwidth when a small resistance is placed between the gate-source terminals of the DM-MOSFETs [16]. A significant advantage with these designs is that the DM-MOSFET of the measurement circuit is a resistive channel.…”