A broadband active harmonic load-pull setup with a modulated generator as active load

This paper proposes an active harmonic load-pull setup which allows the use of broadband test signals and guarantees unconditional stability of the active load. Active loadpull systems with conventional active loops suffer from too high delay times which limit their application to smallhand signals. The proposed system uses a modulated RF source for the generation of the required backward travelling wave. This guarantees unconditional stability of the load and allows a perfect delay compensation. Equations will be given to approximate the modulation signal for backed-off (weakly non-linear) amplifiers.