Practical Method for Obtaining Maximum Channel Temperature of GaAs MMIC

[Abstract] Regressive equations that calculate the maximum channel temperature of a GaAs monolithic microwave integrated circuit (MMIC) have been made through a lot of finite element (FE) analyses. And this paper suggests how to estimate the maximum channel temperature with those regressive equations for frequent cases. As an example, a medium power amplifier’s maximum channel temperature was calculated and its result was larger than that of a complete FE model by about 4%. The medium power amplifier’s temperature distribution was obtained through an infrared scan and, even though the maximum channel temperature could not be obtained due to the test’s inherent shortcoming, temperature other than gate fingers showed good agreement with FE analysis results. Therefore it can be said that the practical method for obtaining the maximum channel temperature using regressive equations can give thermal resistance of a GaAs MMIC very easily and quickly without time-consuming FE analyses.