This article describes the thermal resistance “junction-to-case” measurement results for GaN high-electron mobility transistors (HEMTs). The measurements were taken by using the apparatus which includes two methods of thermal resistance measurements. For the first one that uses standard MIL-STD-750-3, a sequence of heating current pulses passes through the transistor channel and then the junction temperature is measured. The second method uses modulated heating power and measures the response which is a variable component of the junction temperature. To exclude the influence of the heating pulses duration, which is typical for the standard method, preliminary measurements of the transient response of thermal impedance were taken. The analysis of this characteristic allows determining the optimal values of the pulse duration. To reduce the influence of the delay time caused by transient electrical processes in the transistor when it switches from heating mode to the measurement of the thermal sensitive parameter (TSP) mode, the TSP signal was extrapolated to the end of the heating pulse. A comparative analysis shows that the measurement results obtained by the standard and modulation methods differ by less than 2%. The results of a study of the influence of the heating current pulses magnitude on the thermal resistance measurements results are presented. It was found that, as heating current increased, the thermal resistance measured values increased, which indicates the nonlinear nature of the dependence of the temperature in the transistor channel on the power dissipated in it.

中文翻译：

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使用调制方法测量 GaN HEMT 的热阻

本文介绍了 GaN 高电子迁移率晶体管 (HEMT) 的热阻“结到壳”测量结果。测量是通过使用包括两种热阻测量方法的设备进行的。对于使用标准 MIL-STD-750-3 的第一个，一系列加热电流脉冲通过晶体管通道，然后测量结温。第二种方法使用调制加热功率并测量作为结温可变分量的响应。为了排除标准方法中典型的加热脉冲持续时间的影响，对热阻抗的瞬态响应进行了初步测量。对该特性的分析允许确定脉冲持续时间的最佳值。为了减少晶体管从加热模式切换到热敏参数 (TSP) 测量模式时瞬态电过程引起的延迟时间的影响，将 TSP 信号外推到加热脉冲的末尾。对比分析表明，标准方法和调制方法得到的测量结果相差不到2%。介绍了加热电流脉冲幅度对热阻测量结果影响的研究结果。发现随着加热电流的增加，热阻测量值增加，这表明晶体管通道中的温度对其耗散的功率的依赖性是非线性的。