Thermal Coupling in AlGaN/GaN Power Transistors

Thermal coupling in AlGaN/GaN transistors is investigated by means of thermal FEM (finite element method) simulation. The results are combined with electrical network simulation using an electro-thermal model. From the FEM analysis the thermal coupling matrix is established, describing the thermal interaction between the different cells of a power transistor. The matrix allows to extract an equivalent circuit for the thermal coupling in a straightforward way. The electrical transistor model is complemented by thermal ports to connect the cells via the thermal coupling network. The electro-thermal model developed yields information on the distribution of temperature and currents within a powerbar and thus is an important tool in transistor design.