A Fast Two-Tone Active Load-Pull Algorithm for Assessing the Non-linearity of RF Devices

Radio frequency (RF) devices used in modern wireless systems must meet increasingly complicated spectral constraints while still operating with high power efficiency. A fast real-time two-tone active load-pull algorithm is proposed to assess the relationship between nonlinear performance with associated device load impedance variations. This algorithm employs real time measurement data to extract two-tone local nonlinear behaviour model, which is further used for the prediction of injected signal value in the active real-time load-pull system, therefore minimizing the number of iterations required for load emulation. The proposed method was validated on a real two-tone load-pull measurement bench using off-the-shelf instruments. The result shows that the measurement speed has been greatly increased without sacrifice of the impedance emulation accuracy. This intelligent two-tone load-pull algorithm is expected to be applied in the designing of modern communication system and radar transmitters, as well as the validation of the models of radio frequency transistors.