A new nonlinear capacitance model of millimeter wave power PHEMT for accurate AM/AM-AM/PM simulations

A new one-dimensional (1-D) nonlinear gate-source Cgs and gate-drain Cgd capacitance model designed for power-PHEMT transistors is presented. The capacitance values are extracted from measured [S] parameters, along a load-line corresponding to a power performance of an optimum amplifier design. The reliable resulting model predicts adequate power performances with small or large signals in reduced CPU time. This new model is validated by comparisons between load-pull power measurements at 25.5 GHz and harmonic balance simulations. It reveals good accuracy for AM/AM and AM/PM predictions.