Assessment of power-transistor package models: Distributed versus lumped approach

Power transistors basically consist of a number of active transistors that are mounted in parallel inside the package. High powers require large transistor sizes, which translates into significant physical dimensions. For circuit design, on the other hand, a lumped model is favorable for sake of simulation speed and numerical convergence. This paper addresses questions related to reducing the equivalent circuit of a package into a lumped model. A packaged 60 W GaN L-band power transistor is used as an example. Starting from a distributed equivalent circuit, a lumped model is derived, and the accuracies of the models are discussed relating to measurement.