Channel temperature measurement in hermetic packaged GaN HEMTs power switch using fast static and transient thermal methods

Szu Hao Chen, Po Chien Chou, Stone Cheng*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


A GaN-based power device is a superior component for high-frequency and high-efficiency applications and especially for applications that involve megahertz power conversion. In this work, a fast process of static thermal resistance (Rth) and transient thermal impedance (Zth) measurements are made and analyzed to determine the thermal characteristics of the channel temperature of a hermetically packaged GaN power device. Five temperature-sensitive parameters (TSPs) are measured at temperatures from 20 to 160 °C. Measurements and statistical analyses included variations with temperature of on-resistance (Ron), saturation drain current (IDsat), drain conductance (gd), threshold voltage (Vth), and knee voltage (Vknee). The statistical analyses revealed the relationships between the heating curve parameter (Ron) and the cooling curve parameters (Vknee, IDsat, gd, and Vth). The average thermal resistance values are extracted as follows: Maximum Rth is 2.99 °C W−1, minimum Rth is 2.92 °C W−1, and the variation among the five TSPs is <3%. Conventional optical-based techniques such as infrared (IR) and micro-Raman thermography are destructive to packaged devices. Therefore, this study developed the two reliable and fast non-destructive methods for estimating channel temperature with the following features: (1) They elucidate static and transient characteristics; (2) they involve heating and cooling; and (3) they evaluate transient thermal impedance (TTI) and safe operating area (SOA). The heating curve method has advantages over cooling curve method in terms of capturing time (40 vs. 400 s, respectively), and a lower power excitation is required to obtain the transient channel temperature response.

Original languageEnglish
Pages (from-to)1159-1168
Number of pages10
JournalJournal of Thermal Analysis and Calorimetry
Issue number2
StatePublished - 1 Aug 2017


  • Cooling curve
  • Heating curve
  • Junction temperature
  • Power semiconductor device
  • Safe operating area (SOA)
  • Transient thermal impedance (TTI)

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