EMPIRICAL MODELING OF LOW-FREQUENCY DISPERSIVE EFFECTS DUE TO TRAPS AND THERMAL PHENOMENA IN III-V FETS

The modeling of low frequency dispersive effects due to surface state densities, deep level traps and thermal phenomena plays an important r ole in the large-signal performance prediction of III-V FET's. This pa per describes an empirical modeling approach to accurately predict dev iations between static and dynamic drain current characteristics cause d by dispersive effects in III-V devices operating at microwave freque ncies, It is based on reasonable assumptions and can easily be embedde d in nonlinear FET models to be used in Harmonic-Balance tools for cir cuit analysis and design. Experimental and simulated results, for HEMT 's and GaAs MESFET's of different manufacturers, that confirm the vali dity of the new approach, are presented and discussed together with th e characterization procedures required.