寄生电感对低压增强型GaN HEMT开关行为的影响

Influence of Parasitic Inductance on Switching Behavior of Low Voltage E-Mode GaN HEMT

寄生电感是影响功率管开关特性的重要因素之一,开关频率越高,寄生电感对低压增强型氮化镓高电子迁移率晶体管(GaN HEMT)的开关行为影响越深,使其无法发挥高速开关的性能优势。通过建立数学模型,理论分析了考虑各部分寄生电感后增强型GaN HEMT的开关过程,并推导了各阶段的持续时间和影响因素,然后通过建立双脉冲测试平台,对各部分寄生电感对开关特性的具体影响进行了实验验证。实验结果表明,寄生电感会使开关过程中的电流、电压出现振荡,影响开关速度和可靠性,并且各部分寄生电感对增强型GaN HEMT的开关过程影响程度不同,在实际PCB布局受到物理限制时,需要根据设计目标优化布局,合理分配各部分寄生电感以获得最优的开关性能。

Parasitic inductance is one of the most important factors affecting the switching characte-ristics of power transistors. And it has a larger influence on the switching behavior of low voltage E-mode gallium nitride high electron mobility transistors(GaN HEMT) with the increase of switching frequency, which limits full utilization of performance advantages of high speed switching in high frequency applications. By establishing mathematical model, the detailed switching process of E-mode GaN HEMT with each parasitic inductance was analyzed theoretically. The duration and influence factors of each stage were derived. A double-pulse test platform was built to confirm individual influence of each parasitic inductance on switching characteristics by the experiment. The test results show that the parasitic induc-tance will induce the oscillation in current and voltage during the switching process and affect the switching speed and reliability. Moreover, each parasitic inductance has different effects on the switching process of E-mode GaN HEMT. Due to physical limits of practical PCB layout, it is necessary to optimize the layout and distribute each parasitic inductance reasonably according to the design requirements to obtain the best switching performance.