A Scalable X-Parameter Model for GaAs and GaN FETs

A new nonlinear FET model formulation is proposed which comprises an X-parameter (S-function or Poly Harmonic Distortion) intrinsic model combined with lumped extrinsic circuit model shells This enables the correct gate width scaling of the intrinsic and extrinsic model by finger number and unit gate width. An extraction technique is described based on de-embedding the X-parameters to the intrinsic plane. A verification example of scaling of a 10x90um 0.15um pHEMT X-parameter model (generated from a scalable compact model) down to a 4x50um device (a factor of 4.5), is shown without loss of accuracy in power sweep and loadpull contour results compared to the reference compact model simulation.