Improved large-signal model and model extraction procedure for InGaP/GaAs HBTs under high-current operations

Improved large-signal as well as improved model extraction procedure is proposed for InGaP/GaAs HBTs under high-current operations. The model comprises physics-based differential equations that are implemented through symbolically defined devices in a commercially available circuit simulator. Other model improvements include bilateral logical correlation with small-signal characteristics, and additional series resistance with the base-emitter diffusion capacitance. The improvement in extraction procedure is mainly based on a fixed intrinsic vs. extrinsic base-collector capacitance ratio at low currents, whereas a fixed intrinsic base resistance at high currents. Experimentally it has been verified that the as-extracted model without numerical optimization closely predicts the RF power performance of the HBTs.