An Improved Small-Signal Parameter-Extraction Algorithm for GaN HEMT Devices

A highly efficient and accurate extraction algorithm for the small-signal equivalent-circuit parameters of a GaN high electron-mobility transistor device is presented. Elements of the extrinsic equivalent-circuit topology are evaluated using a modified “cold field-effect transistor” approach whereby the undesirable need to forward bias the device's gate terminal is avoided. Intrinsic elements are determined based on a circuit topology, which identifies, for the first time, a time delay in the output conductance of GaN-based devices. The validity of the proposed algorithm has been thoroughly verified with excellent correlation between the measured and modeled $S$-parameters up to 50 GHz.