Abstract

A new table-based large-signal FET model using delayed capacitive currents is developed to account for nonquasi-static features of PHEMTs at high frequency. Unlike conventional models, it does not contain real charge terms and only utilizes capacitance currents and therefore, avoids the problem of path-dependence in the charge integration based on small-signal models. Consideration is also given to the HF dispersion of conductances. It is found that frequency-dependence of conductances is responsible for the deviation in fitting S-parameters at high frequency. Bias-dependent delay times associated with capacitance terms are included in the model. The model features accuracy and simplicity of extraction. It is especially useful for high frequency PHEMTs or FETs with dispersion.