A new small-signal modeling approach applied to GaN devices

A new small-signal modeling approach applied to GaN-based devices is presented. In this approach, a new method for extracting the parasitic elements of the GaN device is developed. This method is based on two steps, which are: 1) using cold S-parameter measurements, high-quality starting values for the extrinsic parameters that would place the extraction close to the global minimum of the objective function for the distributed equivalent circuit model are generated and 2) the optimal model parameter values are searched through optimization using the starting values already obtained. The bias-dependent intrinsic parameter extraction procedure is improved for optimal extraction. The validity of the developed modeling approach and the proposed small-signal model is verified by comparing the simulated wide-band small-signal S-parameter, over a wide bias range, with measured data of a 0.5-μm GaN high electron-mobility transistor with a 2×50 μm gatewidth.