A modified nonlinear Curtice model for pseudomorphic high electron mobility transistors, capable of modeling the current-voltage characteristics, drain-to-source resistances, and gate-to-source and gate-to-drain capacitances, has been developed. Parameters extraction is based on dual delta-doped pseudomorphic high electron mobility transistors on GaAs substrates. Measured and modeled dc I-V, S parameters, and power performance have been compared and demonstrated a great improvement from the conventional Curtice models.