Thermal analysis of high-powered devices using analytical and experimental methods

Thermal characterization of high power microwave devices is important for determining their reliability. Exceeding the optimal temperature will have a detrimental effect on the performance and reliability of these devices. An accurate closed form analytical solution for predicting the channel temperature in a power amplifier Field Effect Transistors (FETs) or a Monolithic Microwave Integrated Circuits (MMICs) has been presented. Its derivation is based on Green´s function integral method on a point heat source developed through method of images. Unlike previous works, the exact location of heat dissipation region is easily taken into account. In addition, present work is easy to implement and reduces the computation time significantly due to absence of double infinite series. This work is also applicable for multiple heat sources by superposition techniques and has been shown to agree well with both the Finite Element Analysis (FEA) and the experimental results. Therefore, this work is useful in predicting the channel temperature in the early stages without having to go through the FEA. Various techniques which are being used to measure temperature of high-power devices are described and its measured temperatures are compared with calculated temperatures using our analytical method. It has been shown that the present work yields result with good accuracy.