Multiphysics Modeling of RF and Microwave High-Power Transistors

In this paper, we present a multiphysics approach for the simulation of high-power RF and microwave transistors, in which electromagnetic, thermal, and nonlinear transistor models are linked together within a harmonic-balance circuit simulator. This approach is used to analyze a laterally diffused metal-oxide-semiconductor (LDMOS) transistor that has a total gate width of 102 mm and operates at 2.14 GHz. The transistor die is placed in a metal-ceramic package, with bond-wire arrays connecting the die to the package leads. The effects of three different gate bond-pad layouts on the transistor efficiency are studied. Through plots of the spatial distributions of the drain efficiency and the time-domain currents and voltages across the die, we reveal for the first time unique interactions between the electromagnetic effects of the layout and the microwave behavior of the large-die LDMOS power field-effect transistor.