A model-base comparison: GaAs/GaAlAs HBT versus silicon bipolar

A pure model-base comparison is made between the GaAs/ GaAlAs HBT and the silicon bipolar transistor for the high-speed switching performance under ring oscillator operation. Full utilization is made of our own modeling tools, which include a "physical" one-dimensional transistor model, a hybrid model to represent a realistic device structure, and a circuit simulator to allow direct access to the physical model. Delay time versus power characteristics, as well as dynamic carrier profiles are demonstrated, with discussion about limiting factors for the switching speed.