Harmonic Load-Pull Techniques: An Overview of Modern Systems

The characterization of microwave devices under nonlinear conditions is fundamental for device technology development, to improve device large signal model accuracy and reliability, as well as an essential tool to support the design of power amplifiers (PAs). Since the input and output device terminations at fundamental and harmonics frequencies play a crucial role to set the device behaviors and performances, load-pull (LP) measurements are today one of the prominent characterization solutions at RF, micro-, and millimeter waves. In this article, a concise but comprehensive overview of the most important LP techniques available today is presented and pros and cons of the several approaches are highlighted and discussed.