Abstract
Dynamic on-resistance ( ${\text{d}R_\text{on}}$ ), where the on-resistance immediately after turn-on is higher than the DC resistance, increases the conduction losses in power converters with gallium nitride high-electron-mobility transistors (GaN HEMTs). There exist no direct ${\text{d}R_\text{on}}$ measurements in the literature above ${1}\,\text{MHz}$ , leaving designers unable to predict conduction losses in emerging multi-MHz applications. We address this literature gap by collecting the first on-state voltage ${\text{d}R_\text{on}}$ measurements at multi-MHz frequencies, with a focus on the zero-voltage-switching conditions that are predominantly employed at high frequency. On the selected commercially-available HEMT with a breakdown voltage below ${200}\,\text{V}$ , the dynamic contribution asymptotes above $\approx {2}\,\text{MHz}$ , a finding predicted by the slow time constants of the traps that cause ${\text{d}R_\text{on}}$ . For the tested HEMT, we find a maximum ${\text{d}R_\text{on}}$ increase over the DC resistance of 2 $\times $ in a multi-MHz, zero-voltage-switched application.
Highlights
Increasing the switching frequency of power converters to the high-frequency (HF) range, between 3 MHz to 30 MHz, is an avenue to reduce passive component size, weight, and cost [1]
Gallium nitride high-electron-mobility transistors (GaN HEMTs) are an especially promising power semiconductor technology for this frequency range [2], but are known to suffer from “current collapse,” or dynamic Ron, where the on-resistance immediately after turn-on is noticeably higher than the nominal, steady-state value (Rdc) [3]. dRon is caused by the trapping of electrons in the GaN HEMT structure, with two dominant mechanisms: off-state trapping and hot electron trapping [4]–[6]
With these electrons trapped in undesirable locations in the structure, the concentration of electrons in the 2-D electron gas (2DEG) must be proportionally reduced to maintain overall charge neutrality
Summary
Increasing the switching frequency of power converters to the high-frequency (HF) range, between 3 MHz to 30 MHz, is an avenue to reduce passive component size, weight, and cost [1]. During the finite time required to detrap these electrons, the device exhibits reduced drain-source current and higher-than-expected on-resistance, or dRon. In high-frequency applications, dRon directly determines conduction losses since dynamic effects dominate the effective on-resistance for the entire conduction period, and the importance of accurate dRon characterization is underscored by a recent dRon-focused JEDEC standard [7]. In high-frequency applications, dRon directly determines conduction losses since dynamic effects dominate the effective on-resistance for the entire conduction period, and the importance of accurate dRon characterization is underscored by a recent dRon-focused JEDEC standard [7] This phenomenon is well-characterized at lower frequencies in commercially-available HEMTs [8], with some discrepancy in methodology and reported values [9]. A physical justification for this asymptote forms the foundation for extrapolating these findings to other GaN-on-Si HEMTs in MHz-frequency, ZVS power converters
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
