Search

A normally-off SiC-JFET/GaN-HEMT cascode device is recently proposed, featuring a cascode configuration that incorporates a high-voltage (i.e., 1200 V) SiC junction field effect transistor (JFET) and a low-voltage GaN high electron mobility transistor (HEMT). This cascode device exhibits superior thermal stability and switching performance compared to the SiC MOSFETs, but also inevitably presents challenge in dv/dt-control as the input gate does not directly control the high-voltage JFET. Since dv/dt-control is of great importance to the management and suppression of electromagnetic interference in power electronics systems, methods of controlling the dv/dt rates of SiC/GaN cascode devices need to be developed. In this article, we conduct systematic investigation on different dv/dt control schemes with theoretical analysis and experimental evaluation. A dv/dt-control method based on diode-clamped external JFET gate resistor is proposed and evaluated by comparing it with other more conventional methods. The proposed dv/dt-control method is verified to provide a balanced dv/dt-control on the device turn-on and turn-off. [ABSTRACT FROM AUTHOR]

A 1200-V/100-mΩ silicon carbide (SiC) junction field-effect-transistor (JFET)/ gallium nitride (GaN) high-electron-mobility-transistor (HEMT) hybrid power switch is demonstrated, which features a flip-chip copackaged cascode configuration incorporating a vertical SiC JFET and a lateral GaN-HEMT. The high-voltage SiC-JFET provides the high-voltage blocking capability while the low-voltage GaN-HEMT enables the normally-off gate control with superior switching characteristics. Compared to conventional SiC-JFET/Si-mosfet cascode devices, the SiC-JFET/GaN-HEMT cascode device exhibits fast switching speed, which has been validated by systematic characterizations including static/dynamic device-level measurements and board-level hard-switching tests. Meanwhile, the device is free from several notorious issues of high-voltage GaN power transistors such as dynamic on-state resistance degradation and threshold voltage shift. Such a wide-bandgap semiconductor-based hybrid switch is suitable to be deployed in high-power and high-efficiency power conversion systems. [ABSTRACT FROM AUTHOR]