CALCULATION OF THE POWER CAPABILITIES OF HBT AMPLIFIERS BASED ON A NEW PHYSICAL HBT MODEL

A novel model for the simulation of the microwave power capabilities o f HBTs is presented. The model is based an physical analytical formula tion of the terminal currents as functions of the base-emitter and bas e-collector voltages. It tal;es into account the unequal thermal distr ibution of temperature for multifinger HBT devices. the impact ionizat ion, tunnelling, recombination currents, etc. From the simulation of m ulti-finger transistor structures it can be concluded that high therma l device resistances are detrimental for power performance, because of the unequal distribution of temperature and, hence, base current in t he BET structure. In can also he concluded that tile input and output reflection coefficients are insensitive to temperature variation, Fina lly, it has been shown theoretically and experimentally that the break down voltage increases slightly with increasing operating temperature. (C) 1996 John Wiley & Sons, Inc.