Application of the TLM method to transient thermal simulation of microwave power transistors

The transmission line matrix (TLM) explicit method of numerical simulation has been used to model the transient thermal properties of various microwave heterojunction bipolar transistor (HBT's) power structures, used in a pulsed mode. Control of the time step during the simulation is of paramount importance and the paper outlines some of the problems encountered using time step control methods currently published and describes an improved algorithm. This improved time step control method has been implemented in a general purpose 3D TLM transient thermal simulator. Some simulation results are described for a variety HBT transistor structures with very different thermal time constants.<
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