A fast multi harmonic active load-pull setup is presented in this paper. The heart of the system is a large signalnetwork analyzer (LSNA, Maury/NMDG MT4463). The LSNA measures the voltage and current time domainwaveforms at the device terminals. The load reflection coefficient (ΓL(f)) is realized by injecting an amplitude andphase controlled signal at the wanted harmonic on the output of the transistor, according to:ΓL(f) = a2(f0)b2(f0)=A(VI, VQ)ej(ω0+θ(VI,VQ))b2(f0)(1)The speed of the system is significantly improved by using the LSNA in modulation mode. This allows formultiple impedance states to be presented during the measurement time of the LSNA. More than 180 impedancestates can be measured within 21 ms. The sample clock of the LSNA and the vector modulators, controlling theload impedance, needs to be synchronized. A digital pattern generator (DPG) is therefore used in the setup toenable the synchronization, and also to trigger the start of the measurement. Furthermore, a new optimizationalgorithm is implemented to reduce the number of iterations needed to realize the desired load impedance. Theoptimization is based on the Newton-Raphson algorithm, and convergence is obtained within 3-5 iterations for oneharmonic. The optimization is carried out simultaneously for all wanted harmonics, and multiple impedance states.This significantly reduce the total measurement time for multi harmonic load-pull measurements
