Introduction
Device characterization is required for power amplifier design, and the ideal form of the device data is a large signal model. With a model, the performance can be analyzed for varying drive and impedance conditions, so complex or multi-stage circuits can be designed. A method of formulating a large signal model is to use a measurement-based behavioral approach, popularized by Keysight Technologies' X-Parameter model and AMCAD's EPHD models. These models are extracted from large-signal nonlinear VNA measurements.