A new method is proposed for the accurate experimental characterization and fully automated extraction of compact nonlinear models for Field-Effect Transistors (FETs). The approach, which leads to a charge-conservative description, is based on a single large-signal measurement under a two-tone sinusoidal wave excitation. A suitable choice of tone frequencies, amplitudes, and bias allows to adequately characterize the transistor over the whole safe operating region. The voltage controlled nonlinear functions describing the two-port FET model can be computed over an arbitrarily dense voltage domain by solving an
overdetermined system of linear equations. These equations are expressed in terms of a new Nonlinear Function Sampling operator based on a bi-periodic Fourier series description of the acquired frequency spectra. The experimental validation is carried out on a 0.25-μm Gallium Nitride (GaN) on Silicon Carbide (SiC) High-Electron Mobility Transistor (HEMT) under continuous-wave (CW) and two-tone excitation (intermodulation distortion test).
