Low Frequency Active Harmonic Load-Pull for Experimental Verification of Power Amplifiers’ Modes

The theory of all the power amplifier classes has been developed based on the transistor’s behavior at the intrinsic current source plane. Therefore, measurements of the transistor’s behavior at that plane are intended to be the best way for experimentally studying it. Considering the advantages offered by time-domain Low Frequency (LF) active harmonic load-pull systems over their high frequency (HF) counterpart, they should be recommendable for investigating the resistive-reactive (R-R) continuous modes based on class-B. In this presentation, the use of a time-domain LF active harmonic load-pull system is proposed for measuring the current and voltage waveforms at the intrinsic current source plane of SiC-MESFET and GaN HEMT packaged transistor operated as a R-R class-J mode. From the current and voltage waveforms, the device’s drain efficiency and output power, loading the transistor with fundamental and harmonic impedances corresponding to design space of R-R class-J modes, are calculated and compared with those predicted by the theory. The goal of this presentation is demonstrating that the R-R Class-J modes can be experimentally studied by using time-domain low-frequency active harmonic load-pull measurements.