Equivalent circuit modeling of static substrate thermal coupling using VCVS representation

A new method is described which allows substrate thermal coupling between active devices to be accurately represented in a circuit simulation environment. The method, based on a substrate thermal equivalent circuit containing resistors and voltage-controlled voltage sources, allows for exact representation of substrate thermal coupling at any number of evaluation points. The topology of the equivalent circuit and derivation of its coefficients is described, and application of the technique to inter- and intradevice thermal effects is illustrated. The method is applied with a simple self-heating compact model representation to a measured GaAs device characteristic exhibiting gain collapse, and is found to accurately predict electrothermal behavior.