X-band behavioral model analysis using an active harmonic source- pull and load-pull measurement system

In order to support CAD design and optimization of Power Amplifiers (PAs), using input second harmonic tuning, it is important that non-linear behavioral device models can accurately describe the high levels of input harmonic injection coupled with output fundamental and harmonic injection. This paper presents a tailored mixing model formulation that was used to extract input and output harmonic model coefficients from a set of simultaneous active harmonic source- and load-pull measurements at 9GHz. It was observed, for specific subsets of data, that a fourth order model was sufficient to model the b_1,2 and b_2,2 waves to a confidence of 99.27% and 99.47% respectively; fully combining these coefficient planes yielded a model capable of describing the b_2,1 waves to a confidence of 99.69% for the whole measurement dataset. To demonstrate the functionality of such a model, it was used within a RF CAD tool to investigate the role of the second harmonic injection´s influence on the efficiency of class-B amplifier operation. Results yielded efficiency increases from 73.35 to 78.72%, and highlighted possible improvements in amplifier reliability.